Use upstream slack-go/slack again (#1018)

82 files changed, 10079 insertions, 0 deletions

diff --git a/vendor/github.com/slack-go/slack/.gitignore b/vendor/github.com/slack-go/slack/.gitignore
new file mode 100644
index 00000000..ac6f3eeb
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/.gitignore
@@ -0,0 +1,3 @@
+*.test
+*~
+.idea/
diff --git a/vendor/github.com/slack-go/slack/.gometalinter.json b/vendor/github.com/slack-go/slack/.gometalinter.json
new file mode 100644
index 00000000..5fa629d4
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/.gometalinter.json
@@ -0,0 +1,14 @@
+{
+  "DisableAll": true,
+  "Enable": [
+    "structcheck",
+    "vet",
+    "misspell",
+    "unconvert",
+    "interfacer",
+    "goimports"
+  ],
+  "Vendor": true,
+  "Exclude": ["vendor"],
+  "Deadline": "300s"
+}
diff --git a/vendor/github.com/slack-go/slack/.travis.yml b/vendor/github.com/slack-go/slack/.travis.yml
new file mode 100644
index 00000000..6a968232
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/.travis.yml
@@ -0,0 +1,39 @@
+language: go
+
+env:
+  - GO111MODULE=on
+
+install: true
+
+before_install:
+  - export PATH=$HOME/gopath/bin:$PATH
+  # install gometalinter
+  - curl -L https://git.io/vp6lP | sh
+
+script:
+  - PATH=$PWD/bin:$PATH gometalinter ./...
+  - go test -race -cover ./...
+
+matrix:
+  allow_failures:
+    - go: tip
+  include:
+  - go: "1.7.x"
+    script:  go test -v ./...
+  - go: "1.8.x"
+    script:  go test -v ./...
+  - go: "1.9.x"
+    script:  go test -v ./...
+  - go: "1.10.x"
+    script:  go test -v ./...
+  - go: "1.11.x"
+    script: go test -v -mod=vendor ./...
+  - go: "1.12.x"
+    script: go test -v -mod=vendor ./...
+  - go: "1.13.x"
+    script: go test -v -mod=vendor ./...
+  - go: "tip"
+    script: go test -v -mod=vendor ./...
+
+git:
+  depth: 10
diff --git a/vendor/github.com/slack-go/slack/CHANGELOG.md b/vendor/github.com/slack-go/slack/CHANGELOG.md
new file mode 100644
index 00000000..48bcce55
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/CHANGELOG.md
@@ -0,0 +1,59 @@
+### v0.6.0 - August 31, 2019

+full differences can be viewed using `git log --oneline --decorate --color v0.5.0..v0.6.0`

+thanks to everyone who has contributed since January!

+

+

+#### Breaking Changes:

+- Info struct has had fields removed related to deprecated functionality by slack.

+- minor adjustments to some structs.

+- some internal default values have changed, usually to be more inline with slack defaults or to correct inability to set a particular value. (Message Parse for example.)

+

+##### Highlights:

+- new slacktest package easy mocking for slack client. use, enjoy, please submit PRs for improvements and default behaviours! shamelessly taken from the [slack-test repo](https://github.com/lusis/slack-test) thank you lusis for letting us use it and bring it into the slack repo.

+- blocks, blocks, blocks.

+- RTM ManagedConnection has undergone a significant cleanup.

+in particular handles backoffs gracefully, removed many deadlocks,

+and Disconnect is now much more responsive.

+

+### v0.5.0 - January 20, 2019

+full differences can be viewed using `git log --oneline --decorate --color v0.4.0..v0.5.0`

+- Breaking changes: various old struct fields have been removed or updated to match slack's api.

+- deadlock fix in RTM disconnect.

+

+### v0.4.0 - October 06, 2018

+full differences can be viewed using `git log --oneline --decorate --color v0.3.0..v0.4.0`

+- Breaking Change: renamed ApplyMessageOption, to mark it as unsafe,

+this means it may break without warning in the future.

+- Breaking: Msg structure files field changed to an array.

+- General: implementation for new security headers.

+- RTM: deadlock fix between connect/disconnect.

+- Events: various new fields added.

+- Web: various fixes, new fields exposed, new methods added.

+- Interactions: minor additions expect breaking changes in next release for dialogs/button clicks.

+- Utils: new methods added.

+

+### v0.3.0 - July 30, 2018

+full differences can be viewed using `git log --oneline --decorate --color v0.2.0..v0.3.0`

+- slack events initial support added. (still considered experimental and undergoing changes, stability not promised)

+- vendored depedencies using dep, ensure using up to date tooling before filing issues.

+- RTM has improved its ability to identify dead connections and reconnect automatically (worth calling out in case it has unintended side effects).

+- bug fixes (various timestamp handling, error handling, RTM locking, etc).

+

+### v0.2.0 - Feb 10, 2018

+

+Release adds a bunch of functionality and improvements, mainly to give people a recent version to vendor against.

+

+Please check [0.2.0](https://github.com/nlopes/slack/releases/tag/v0.2.0)

+

+### v0.1.0 - May 28, 2017

+

+This is released before adding context support.

+As the used context package is the one from Go 1.7 this will be the last

+compatible with Go < 1.7.

+

+Please check [0.1.0](https://github.com/nlopes/slack/releases/tag/v0.1.0)

+

+### v0.0.1 - Jul 26, 2015

+

+If you just updated from master and it broke your implementation, please

+check [0.0.1](https://github.com/nlopes/slack/releases/tag/v0.0.1)

diff --git a/vendor/github.com/slack-go/slack/LICENSE b/vendor/github.com/slack-go/slack/LICENSE
new file mode 100644
index 00000000..5145171f
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/LICENSE
@@ -0,0 +1,23 @@
+Copyright (c) 2015, Norberto Lopes
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without modification,
+are permitted provided that the following conditions are met:
+
+1. Redistributions of source code must retain the above copyright notice, this
+list of conditions and the following disclaimer.
+
+2. Redistributions in binary form must reproduce the above copyright notice,
+this list of conditions and the following disclaimer in the documentation and/or
+other materials provided with the distribution.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
+ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
diff --git a/vendor/github.com/slack-go/slack/Makefile b/vendor/github.com/slack-go/slack/Makefile
new file mode 100644
index 00000000..1c64747d
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/Makefile
@@ -0,0 +1,36 @@
+.PHONY: help deps fmt lint test test-race test-integration
+
+help:
+	@echo ""
+	@echo "Welcome to slack-go/slack make."
+	@echo "The following commands are available:"
+	@echo ""
+	@echo "    make deps              : Fetch all dependencies"
+	@echo "    make fmt               : Run go fmt to fix any formatting issues"
+	@echo "    make lint              : Use go vet to check for linting issues"
+	@echo "    make test              : Run all short tests"
+	@echo "    make test-race         : Run all tests with race condition checking"
+	@echo "    make test-integration  : Run all tests without limiting to short"
+	@echo ""
+	@echo "    make pr-prep           : Run this before making a PR to run fmt, lint and tests"
+	@echo ""
+
+deps:
+	@go mod tidy
+
+fmt:
+	@go fmt .
+
+lint:
+	@go vet .
+
+test:
+	@go test -count=1 -timeout 300s -short .
+
+test-race:
+	@go test -count=1 -timeout 300s -short -race .
+
+test-integration:
+	@go test -count=1 -timeout 600s .
+
+pr-prep: fmt lint test-race test-integration
diff --git a/vendor/github.com/slack-go/slack/README.md b/vendor/github.com/slack-go/slack/README.md
new file mode 100644
index 00000000..eaf07782
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/README.md
@@ -0,0 +1,96 @@
+Slack API in Go [![GoDoc](https://godoc.org/github.com/slack-go/slack?status.svg)](https://godoc.org/github.com/slack-go/slack) [![Build Status](https://travis-ci.org/slack-go/slack.svg)](https://travis-ci.org/slack-go/slack)
+===============
+This is the original Slack library for Go created by Norberto Lopez, transferred to a Github organization.
+
+[![Join the chat at https://gitter.im/go-slack/Lobby](https://badges.gitter.im/go-slack/Lobby.svg)](https://gitter.im/go-slack/Lobby?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge)
+
+This library supports most if not all of the `api.slack.com` REST
+calls, as well as the Real-Time Messaging protocol over websocket, in
+a fully managed way.
+
+
+
+
+## Changelog
+
+[CHANGELOG.md](https://github.com/slack-go/slack/blob/master/CHANGELOG.md) is available. Please visit it for updates.
+
+## Installing
+
+### *go get*
+
+    $ go get -u github.com/slack-go/slack
+
+## Example
+
+### Getting all groups
+
+```golang
+import (
+	"fmt"
+
+	"github.com/slack-go/slack"
+)
+
+func main() {
+	api := slack.New("YOUR_TOKEN_HERE")
+	// If you set debugging, it will log all requests to the console
+	// Useful when encountering issues
+	// slack.New("YOUR_TOKEN_HERE", slack.OptionDebug(true))
+	groups, err := api.GetGroups(false)
+	if err != nil {
+		fmt.Printf("%s\n", err)
+		return
+	}
+	for _, group := range groups {
+		fmt.Printf("ID: %s, Name: %s\n", group.ID, group.Name)
+	}
+}
+```
+
+### Getting User Information
+
+```golang
+import (
+    "fmt"
+
+    "github.com/slack-go/slack"
+)
+
+func main() {
+    api := slack.New("YOUR_TOKEN_HERE")
+    user, err := api.GetUserInfo("U023BECGF")
+    if err != nil {
+	    fmt.Printf("%s\n", err)
+	    return
+    }
+    fmt.Printf("ID: %s, Fullname: %s, Email: %s\n", user.ID, user.Profile.RealName, user.Profile.Email)
+}
+```
+
+## Minimal RTM usage:
+
+See https://github.com/slack-go/slack/blob/master/examples/websocket/websocket.go
+
+
+## Minimal EventsAPI usage:
+
+See https://github.com/slack-go/slack/blob/master/examples/eventsapi/events.go
+
+
+## Contributing
+
+You are more than welcome to contribute to this project.  Fork and
+make a Pull Request, or create an Issue if you see any problem.
+
+Before making any Pull Request please run the following:
+
+```
+make pr-prep
+```
+
+This will check/update code formatting, linting and then run all tests
+
+## License
+
+BSD 2 Clause license
diff --git a/vendor/github.com/slack-go/slack/TODO.txt b/vendor/github.com/slack-go/slack/TODO.txt
new file mode 100644
index 00000000..8607960b
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/TODO.txt
@@ -0,0 +1,3 @@
+- Add more tests!!!
+- Add support to have markdown hints
+  - See section Message Formatting at https://api.slack.com/docs/formatting
diff --git a/vendor/github.com/slack-go/slack/admin.go b/vendor/github.com/slack-go/slack/admin.go
new file mode 100644
index 00000000..d51426b5
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/admin.go
@@ -0,0 +1,207 @@
+package slack
+
+import (
+	"context"
+	"fmt"
+	"net/url"
+	"strings"
+)
+
+func (api *Client) adminRequest(ctx context.Context, method string, teamName string, values url.Values) error {
+	resp := &SlackResponse{}
+	err := parseAdminResponse(ctx, api.httpclient, method, teamName, values, resp, api)
+	if err != nil {
+		return err
+	}
+
+	return resp.Err()
+}
+
+// DisableUser disabled a user account, given a user ID
+func (api *Client) DisableUser(teamName string, uid string) error {
+	return api.DisableUserContext(context.Background(), teamName, uid)
+}
+
+// DisableUserContext disabled a user account, given a user ID with a custom context
+func (api *Client) DisableUserContext(ctx context.Context, teamName string, uid string) error {
+	values := url.Values{
+		"user":       {uid},
+		"token":      {api.token},
+		"set_active": {"true"},
+		"_attempts":  {"1"},
+	}
+
+	if err := api.adminRequest(ctx, "setInactive", teamName, values); err != nil {
+		return fmt.Errorf("failed to disable user with id '%s': %s", uid, err)
+	}
+
+	return nil
+}
+
+// InviteGuest invites a user to Slack as a single-channel guest
+func (api *Client) InviteGuest(teamName, channel, firstName, lastName, emailAddress string) error {
+	return api.InviteGuestContext(context.Background(), teamName, channel, firstName, lastName, emailAddress)
+}
+
+// InviteGuestContext invites a user to Slack as a single-channel guest with a custom context
+func (api *Client) InviteGuestContext(ctx context.Context, teamName, channel, firstName, lastName, emailAddress string) error {
+	values := url.Values{
+		"email":            {emailAddress},
+		"channels":         {channel},
+		"first_name":       {firstName},
+		"last_name":        {lastName},
+		"ultra_restricted": {"1"},
+		"token":            {api.token},
+		"resend":           {"true"},
+		"set_active":       {"true"},
+		"_attempts":        {"1"},
+	}
+
+	err := api.adminRequest(ctx, "invite", teamName, values)
+	if err != nil {
+		return fmt.Errorf("Failed to invite single-channel guest: %s", err)
+	}
+
+	return nil
+}
+
+// InviteRestricted invites a user to Slack as a restricted account
+func (api *Client) InviteRestricted(teamName, channel, firstName, lastName, emailAddress string) error {
+	return api.InviteRestrictedContext(context.Background(), teamName, channel, firstName, lastName, emailAddress)
+}
+
+// InviteRestrictedContext invites a user to Slack as a restricted account with a custom context
+func (api *Client) InviteRestrictedContext(ctx context.Context, teamName, channel, firstName, lastName, emailAddress string) error {
+	values := url.Values{
+		"email":      {emailAddress},
+		"channels":   {channel},
+		"first_name": {firstName},
+		"last_name":  {lastName},
+		"restricted": {"1"},
+		"token":      {api.token},
+		"resend":     {"true"},
+		"set_active": {"true"},
+		"_attempts":  {"1"},
+	}
+
+	err := api.adminRequest(ctx, "invite", teamName, values)
+	if err != nil {
+		return fmt.Errorf("Failed to restricted account: %s", err)
+	}
+
+	return nil
+}
+
+// InviteToTeam invites a user to a Slack team
+func (api *Client) InviteToTeam(teamName, firstName, lastName, emailAddress string) error {
+	return api.InviteToTeamContext(context.Background(), teamName, firstName, lastName, emailAddress)
+}
+
+// InviteToTeamContext invites a user to a Slack team with a custom context
+func (api *Client) InviteToTeamContext(ctx context.Context, teamName, firstName, lastName, emailAddress string) error {
+	values := url.Values{
+		"email":      {emailAddress},
+		"first_name": {firstName},
+		"last_name":  {lastName},
+		"token":      {api.token},
+		"set_active": {"true"},
+		"_attempts":  {"1"},
+	}
+
+	err := api.adminRequest(ctx, "invite", teamName, values)
+	if err != nil {
+		return fmt.Errorf("Failed to invite to team: %s", err)
+	}
+
+	return nil
+}
+
+// SetRegular enables the specified user
+func (api *Client) SetRegular(teamName, user string) error {
+	return api.SetRegularContext(context.Background(), teamName, user)
+}
+
+// SetRegularContext enables the specified user with a custom context
+func (api *Client) SetRegularContext(ctx context.Context, teamName, user string) error {
+	values := url.Values{
+		"user":       {user},
+		"token":      {api.token},
+		"set_active": {"true"},
+		"_attempts":  {"1"},
+	}
+
+	err := api.adminRequest(ctx, "setRegular", teamName, values)
+	if err != nil {
+		return fmt.Errorf("Failed to change the user (%s) to a regular user: %s", user, err)
+	}
+
+	return nil
+}
+
+// SendSSOBindingEmail sends an SSO binding email to the specified user
+func (api *Client) SendSSOBindingEmail(teamName, user string) error {
+	return api.SendSSOBindingEmailContext(context.Background(), teamName, user)
+}
+
+// SendSSOBindingEmailContext sends an SSO binding email to the specified user with a custom context
+func (api *Client) SendSSOBindingEmailContext(ctx context.Context, teamName, user string) error {
+	values := url.Values{
+		"user":       {user},
+		"token":      {api.token},
+		"set_active": {"true"},
+		"_attempts":  {"1"},
+	}
+
+	err := api.adminRequest(ctx, "sendSSOBind", teamName, values)
+	if err != nil {
+		return fmt.Errorf("Failed to send SSO binding email for user (%s): %s", user, err)
+	}
+
+	return nil
+}
+
+// SetUltraRestricted converts a user into a single-channel guest
+func (api *Client) SetUltraRestricted(teamName, uid, channel string) error {
+	return api.SetUltraRestrictedContext(context.Background(), teamName, uid, channel)
+}
+
+// SetUltraRestrictedContext converts a user into a single-channel guest with a custom context
+func (api *Client) SetUltraRestrictedContext(ctx context.Context, teamName, uid, channel string) error {
+	values := url.Values{
+		"user":       {uid},
+		"channel":    {channel},
+		"token":      {api.token},
+		"set_active": {"true"},
+		"_attempts":  {"1"},
+	}
+
+	err := api.adminRequest(ctx, "setUltraRestricted", teamName, values)
+	if err != nil {
+		return fmt.Errorf("Failed to ultra-restrict account: %s", err)
+	}
+
+	return nil
+}
+
+// SetRestricted converts a user into a restricted account
+func (api *Client) SetRestricted(teamName, uid string, channelIds ...string) error {
+	return api.SetRestrictedContext(context.Background(), teamName, uid, channelIds...)
+}
+
+// SetRestrictedContext converts a user into a restricted account with a custom context
+func (api *Client) SetRestrictedContext(ctx context.Context, teamName, uid string, channelIds ...string) error {
+	values := url.Values{
+		"user":       {uid},
+		"token":      {api.token},
+		"set_active": {"true"},
+		"_attempts":  {"1"},
+		"channels":   {strings.Join(channelIds, ",")},
+	}
+
+	err := api.adminRequest(ctx, "setRestricted", teamName, values)
+	if err != nil {
+		return fmt.Errorf("failed to restrict account: %s", err)
+	}
+
+	return nil
+}
diff --git a/vendor/github.com/slack-go/slack/attachments.go b/vendor/github.com/slack-go/slack/attachments.go
new file mode 100644
index 00000000..b5b79f9f
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/attachments.go
@@ -0,0 +1,93 @@
+package slack
+
+import "encoding/json"
+
+// AttachmentField contains information for an attachment field
+// An Attachment can contain multiple of these
+type AttachmentField struct {
+	Title string `json:"title"`
+	Value string `json:"value"`
+	Short bool   `json:"short"`
+}
+
+// AttachmentAction is a button or menu to be included in the attachment. Required when
+// using message buttons or menus and otherwise not useful. A maximum of 5 actions may be
+// provided per attachment.
+type AttachmentAction struct {
+	Name            string                        `json:"name"`                       // Required.
+	Text            string                        `json:"text"`                       // Required.
+	Style           string                        `json:"style,omitempty"`            // Optional. Allowed values: "default", "primary", "danger".
+	Type            actionType                    `json:"type"`                       // Required. Must be set to "button" or "select".
+	Value           string                        `json:"value,omitempty"`            // Optional.
+	DataSource      string                        `json:"data_source,omitempty"`      // Optional.
+	MinQueryLength  int                           `json:"min_query_length,omitempty"` // Optional. Default value is 1.
+	Options         []AttachmentActionOption      `json:"options,omitempty"`          // Optional. Maximum of 100 options can be provided in each menu.
+	SelectedOptions []AttachmentActionOption      `json:"selected_options,omitempty"` // Optional. The first element of this array will be set as the pre-selected option for this menu.
+	OptionGroups    []AttachmentActionOptionGroup `json:"option_groups,omitempty"`    // Optional.
+	Confirm         *ConfirmationField            `json:"confirm,omitempty"`          // Optional.
+	URL             string                        `json:"url,omitempty"`              // Optional.
+}
+
+// actionType returns the type of the action
+func (a AttachmentAction) actionType() actionType {
+	return a.Type
+}
+
+// AttachmentActionOption the individual option to appear in action menu.
+type AttachmentActionOption struct {
+	Text        string `json:"text"`                  // Required.
+	Value       string `json:"value"`                 // Required.
+	Description string `json:"description,omitempty"` // Optional. Up to 30 characters.
+}
+
+// AttachmentActionOptionGroup is a semi-hierarchal way to list available options to appear in action menu.
+type AttachmentActionOptionGroup struct {
+	Text    string                   `json:"text"`    // Required.
+	Options []AttachmentActionOption `json:"options"` // Required.
+}
+
+// AttachmentActionCallback is sent from Slack when a user clicks a button in an interactive message (aka AttachmentAction)
+// DEPRECATED: use InteractionCallback
+type AttachmentActionCallback InteractionCallback
+
+// ConfirmationField are used to ask users to confirm actions
+type ConfirmationField struct {
+	Title       string `json:"title,omitempty"`        // Optional.
+	Text        string `json:"text"`                   // Required.
+	OkText      string `json:"ok_text,omitempty"`      // Optional. Defaults to "Okay"
+	DismissText string `json:"dismiss_text,omitempty"` // Optional. Defaults to "Cancel"
+}
+
+// Attachment contains all the information for an attachment
+type Attachment struct {
+	Color    string `json:"color,omitempty"`
+	Fallback string `json:"fallback,omitempty"`
+
+	CallbackID string `json:"callback_id,omitempty"`
+	ID         int    `json:"id,omitempty"`
+
+	AuthorID      string `json:"author_id,omitempty"`
+	AuthorName    string `json:"author_name,omitempty"`
+	AuthorSubname string `json:"author_subname,omitempty"`
+	AuthorLink    string `json:"author_link,omitempty"`
+	AuthorIcon    string `json:"author_icon,omitempty"`
+
+	Title     string `json:"title,omitempty"`
+	TitleLink string `json:"title_link,omitempty"`
+	Pretext   string `json:"pretext,omitempty"`
+	Text      string `json:"text,omitempty"`
+
+	ImageURL string `json:"image_url,omitempty"`
+	ThumbURL string `json:"thumb_url,omitempty"`
+
+	Fields     []AttachmentField  `json:"fields,omitempty"`
+	Actions    []AttachmentAction `json:"actions,omitempty"`
+	MarkdownIn []string           `json:"mrkdwn_in,omitempty"`
+
+	Blocks Blocks `json:"blocks,omitempty"`
+
+	Footer     string `json:"footer,omitempty"`
+	FooterIcon string `json:"footer_icon,omitempty"`
+
+	Ts json.Number `json:"ts,omitempty"`
+}
diff --git a/vendor/github.com/slack-go/slack/auth.go b/vendor/github.com/slack-go/slack/auth.go
new file mode 100644
index 00000000..dc1dbcdf
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/auth.go
@@ -0,0 +1,40 @@
+package slack
+
+import (
+	"context"
+	"net/url"
+)
+
+// AuthRevokeResponse contains our Auth response from the auth.revoke endpoint
+type AuthRevokeResponse struct {
+	SlackResponse      // Contains the "ok", and "Error", if any
+	Revoked       bool `json:"revoked,omitempty"`
+}
+
+// authRequest sends the actual request, and unmarshals the response
+func (api *Client) authRequest(ctx context.Context, path string, values url.Values) (*AuthRevokeResponse, error) {
+	response := &AuthRevokeResponse{}
+	err := api.postMethod(ctx, path, values, response)
+	if err != nil {
+		return nil, err
+	}
+
+	return response, response.Err()
+}
+
+// SendAuthRevoke will send a revocation for our token
+func (api *Client) SendAuthRevoke(token string) (*AuthRevokeResponse, error) {
+	return api.SendAuthRevokeContext(context.Background(), token)
+}
+
+// SendAuthRevokeContext will retrieve the satus from api.test
+func (api *Client) SendAuthRevokeContext(ctx context.Context, token string) (*AuthRevokeResponse, error) {
+	if token == "" {
+		token = api.token
+	}
+	values := url.Values{
+		"token": {token},
+	}
+
+	return api.authRequest(ctx, "auth.revoke", values)
+}
diff --git a/vendor/github.com/slack-go/slack/backoff.go b/vendor/github.com/slack-go/slack/backoff.go
new file mode 100644
index 00000000..2ba697e7
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/backoff.go
@@ -0,0 +1,57 @@
+package slack
+
+import (
+	"math/rand"
+	"time"
+)
+
+// This one was ripped from https://github.com/jpillora/backoff/blob/master/backoff.go
+
+// Backoff is a time.Duration counter. It starts at Min.  After every
+// call to Duration() it is multiplied by Factor.  It is capped at
+// Max. It returns to Min on every call to Reset().  Used in
+// conjunction with the time package.
+type backoff struct {
+	attempts int
+	// Initial value to scale out
+	Initial time.Duration
+	// Jitter value randomizes an additional delay between 0 and Jitter
+	Jitter time.Duration
+	// Max maximum values of the backoff
+	Max time.Duration
+}
+
+// Returns the current value of the counter and then multiplies it
+// Factor
+func (b *backoff) Duration() (dur time.Duration) {
+	// Zero-values are nonsensical, so we use
+	// them to apply defaults
+	if b.Max == 0 {
+		b.Max = 10 * time.Second
+	}
+
+	if b.Initial == 0 {
+		b.Initial = 100 * time.Millisecond
+	}
+
+	// calculate this duration
+	if dur = time.Duration(1 << uint(b.attempts)); dur > 0 {
+		dur = dur * b.Initial
+	} else {
+		dur = b.Max
+	}
+
+	if b.Jitter > 0 {
+		dur = dur + time.Duration(rand.Intn(int(b.Jitter)))
+	}
+
+	// bump attempts count
+	b.attempts++
+
+	return dur
+}
+
+//Resets the current value of the counter back to Min
+func (b *backoff) Reset() {
+	b.attempts = 0
+}
diff --git a/vendor/github.com/slack-go/slack/block.go b/vendor/github.com/slack-go/slack/block.go
new file mode 100644
index 00000000..32ff260c
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/block.go
@@ -0,0 +1,73 @@
+package slack
+
+// @NOTE: Blocks are in beta and subject to change.
+
+// More Information: https://api.slack.com/block-kit
+
+// MessageBlockType defines a named string type to define each block type
+// as a constant for use within the package.
+type MessageBlockType string
+
+const (
+	MBTSection MessageBlockType = "section"
+	MBTDivider MessageBlockType = "divider"
+	MBTImage   MessageBlockType = "image"
+	MBTAction  MessageBlockType = "actions"
+	MBTContext MessageBlockType = "context"
+	MBTInput   MessageBlockType = "input"
+)
+
+// Block defines an interface all block types should implement
+// to ensure consistency between blocks.
+type Block interface {
+	BlockType() MessageBlockType
+}
+
+// Blocks is a convenience struct defined to allow dynamic unmarshalling of
+// the "blocks" value in Slack's JSON response, which varies depending on block type
+type Blocks struct {
+	BlockSet []Block `json:"blocks,omitempty"`
+}
+
+// BlockAction is the action callback sent when a block is interacted with
+type BlockAction struct {
+	ActionID             string              `json:"action_id"`
+	BlockID              string              `json:"block_id"`
+	Type                 actionType          `json:"type"`
+	Text                 TextBlockObject     `json:"text"`
+	Value                string              `json:"value"`
+	ActionTs             string              `json:"action_ts"`
+	SelectedOption       OptionBlockObject   `json:"selected_option"`
+	SelectedOptions      []OptionBlockObject `json:"selected_options"`
+	SelectedUser         string              `json:"selected_user"`
+	SelectedChannel      string              `json:"selected_channel"`
+	SelectedConversation string              `json:"selected_conversation"`
+	SelectedDate         string              `json:"selected_date"`
+	InitialOption        OptionBlockObject   `json:"initial_option"`
+	InitialUser          string              `json:"initial_user"`
+	InitialChannel       string              `json:"initial_channel"`
+	InitialConversation  string              `json:"initial_conversation"`
+	InitialDate          string              `json:"initial_date"`
+}
+
+// actionType returns the type of the action
+func (b BlockAction) actionType() actionType {
+	return b.Type
+}
+
+// NewBlockMessage creates a new Message that contains one or more blocks to be displayed
+func NewBlockMessage(blocks ...Block) Message {
+	return Message{
+		Msg: Msg{
+			Blocks: Blocks{
+				BlockSet: blocks,
+			},
+		},
+	}
+}
+
+// AddBlockMessage appends a block to the end of the existing list of blocks
+func AddBlockMessage(message Message, newBlk Block) Message {
+	message.Msg.Blocks.BlockSet = append(message.Msg.Blocks.BlockSet, newBlk)
+	return message
+}
diff --git a/vendor/github.com/slack-go/slack/block_action.go b/vendor/github.com/slack-go/slack/block_action.go
new file mode 100644
index 00000000..fe46a95c
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/block_action.go
@@ -0,0 +1,26 @@
+package slack
+
+// ActionBlock defines data that is used to hold interactive elements.
+//
+// More Information: https://api.slack.com/reference/messaging/blocks#actions
+type ActionBlock struct {
+	Type     MessageBlockType `json:"type"`
+	BlockID  string           `json:"block_id,omitempty"`
+	Elements BlockElements    `json:"elements"`
+}
+
+// BlockType returns the type of the block
+func (s ActionBlock) BlockType() MessageBlockType {
+	return s.Type
+}
+
+// NewActionBlock returns a new instance of an Action Block
+func NewActionBlock(blockID string, elements ...BlockElement) *ActionBlock {
+	return &ActionBlock{
+		Type:    MBTAction,
+		BlockID: blockID,
+		Elements: BlockElements{
+			ElementSet: elements,
+		},
+	}
+}
diff --git a/vendor/github.com/slack-go/slack/block_context.go b/vendor/github.com/slack-go/slack/block_context.go
new file mode 100644
index 00000000..c37bf27e
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/block_context.go
@@ -0,0 +1,32 @@
+package slack
+
+// ContextBlock defines data that is used to display message context, which can
+// include both images and text.
+//
+// More Information: https://api.slack.com/reference/messaging/blocks#actions
+type ContextBlock struct {
+	Type            MessageBlockType `json:"type"`
+	BlockID         string           `json:"block_id,omitempty"`
+	ContextElements ContextElements  `json:"elements"`
+}
+
+// BlockType returns the type of the block
+func (s ContextBlock) BlockType() MessageBlockType {
+	return s.Type
+}
+
+type ContextElements struct {
+	Elements []MixedElement
+}
+
+// NewContextBlock returns a new instance of a context block
+func NewContextBlock(blockID string, mixedElements ...MixedElement) *ContextBlock {
+	elements := ContextElements{
+		Elements: mixedElements,
+	}
+	return &ContextBlock{
+		Type:            MBTContext,
+		BlockID:         blockID,
+		ContextElements: elements,
+	}
+}
diff --git a/vendor/github.com/slack-go/slack/block_conv.go b/vendor/github.com/slack-go/slack/block_conv.go
new file mode 100644
index 00000000..ce48ce19
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/block_conv.go
@@ -0,0 +1,353 @@
+package slack
+
+import (
+	"encoding/json"
+
+	"github.com/pkg/errors"
+)
+
+type sumtype struct {
+	TypeVal string `json:"type"`
+}
+
+// MarshalJSON implements the Marshaller interface for Blocks so that any JSON
+// marshalling is delegated and proper type determination can be made before marshal
+func (b Blocks) MarshalJSON() ([]byte, error) {
+	bytes, err := json.Marshal(b.BlockSet)
+	if err != nil {
+		return nil, err
+	}
+
+	return bytes, nil
+}
+
+// UnmarshalJSON implements the Unmarshaller interface for Blocks, so that any JSON
+// unmarshalling is delegated and proper type determination can be made before unmarshal
+func (b *Blocks) UnmarshalJSON(data []byte) error {
+	var raw []json.RawMessage
+
+	if string(data) == "{}" {
+		return nil
+	}
+
+	err := json.Unmarshal(data, &raw)
+	if err != nil {
+		return err
+	}
+
+	var blocks Blocks
+	for _, r := range raw {
+		s := sumtype{}
+		err := json.Unmarshal(r, &s)
+		if err != nil {
+			return err
+		}
+
+		var blockType string
+		if s.TypeVal != "" {
+			blockType = s.TypeVal
+		}
+
+		var block Block
+		switch blockType {
+		case "actions":
+			block = &ActionBlock{}
+		case "context":
+			block = &ContextBlock{}
+		case "divider":
+			block = &DividerBlock{}
+		case "image":
+			block = &ImageBlock{}
+		case "input":
+			block = &InputBlock{}
+		case "section":
+			block = &SectionBlock{}
+		case "rich_text":
+			// for now ignore the (complex) content of rich_text blocks until we can fully support it
+			continue
+		case "file":
+			// for now ignore the file blocks until we can fully support it
+			continue
+		default:
+			return errors.New("unsupported block type")
+		}
+
+		err = json.Unmarshal(r, block)
+		if err != nil {
+			return err
+		}
+
+		blocks.BlockSet = append(blocks.BlockSet, block)
+	}
+
+	*b = blocks
+	return nil
+}
+
+// UnmarshalJSON implements the Unmarshaller interface for InputBlock, so that any JSON
+// unmarshalling is delegated and proper type determination can be made before unmarshal
+func (b *InputBlock) UnmarshalJSON(data []byte) error {
+	type alias InputBlock
+	a := struct {
+		Element json.RawMessage `json:"element"`
+		*alias
+	}{
+		alias: (*alias)(b),
+	}
+
+	if err := json.Unmarshal(data, &a); err != nil {
+		return err
+	}
+
+	s := sumtype{}
+	if err := json.Unmarshal(a.Element, &s); err != nil {
+		return nil
+	}
+
+	var e BlockElement
+	switch s.TypeVal {
+	case "datepicker":
+		e = &DatePickerBlockElement{}
+	case "plain_text_input":
+		e = &PlainTextInputBlockElement{}
+	case "static_select", "external_select", "users_select", "conversations_select", "channels_select":
+		e = &SelectBlockElement{}
+	default:
+		return errors.New("unsupported block element type")
+	}
+
+	if err := json.Unmarshal(a.Element, e); err != nil {
+		return err
+	}
+	b.Element = e
+
+	return nil
+}
+
+// MarshalJSON implements the Marshaller interface for BlockElements so that any JSON
+// marshalling is delegated and proper type determination can be made before marshal
+func (b *BlockElements) MarshalJSON() ([]byte, error) {
+	bytes, err := json.Marshal(b.ElementSet)
+	if err != nil {
+		return nil, err
+	}
+
+	return bytes, nil
+}
+
+// UnmarshalJSON implements the Unmarshaller interface for BlockElements, so that any JSON
+// unmarshalling is delegated and proper type determination can be made before unmarshal
+func (b *BlockElements) UnmarshalJSON(data []byte) error {
+	var raw []json.RawMessage
+
+	if string(data) == "{}" {
+		return nil
+	}
+
+	err := json.Unmarshal(data, &raw)
+	if err != nil {
+		return err
+	}
+
+	var blockElements BlockElements
+	for _, r := range raw {
+		s := sumtype{}
+		err := json.Unmarshal(r, &s)
+		if err != nil {
+			return err
+		}
+
+		var blockElementType string
+		if s.TypeVal != "" {
+			blockElementType = s.TypeVal
+		}
+
+		var blockElement BlockElement
+		switch blockElementType {
+		case "image":
+			blockElement = &ImageBlockElement{}
+		case "button":
+			blockElement = &ButtonBlockElement{}
+		case "overflow":
+			blockElement = &OverflowBlockElement{}
+		case "datepicker":
+			blockElement = &DatePickerBlockElement{}
+		case "plain_text_input":
+			blockElement = &PlainTextInputBlockElement{}
+		case "static_select", "external_select", "users_select", "conversations_select", "channels_select":
+			blockElement = &SelectBlockElement{}
+		default:
+			return errors.New("unsupported block element type")
+		}
+
+		err = json.Unmarshal(r, blockElement)
+		if err != nil {
+			return err
+		}
+
+		blockElements.ElementSet = append(blockElements.ElementSet, blockElement)
+	}
+
+	*b = blockElements
+	return nil
+}
+
+// MarshalJSON implements the Marshaller interface for Accessory so that any JSON
+// marshalling is delegated and proper type determination can be made before marshal
+func (a *Accessory) MarshalJSON() ([]byte, error) {
+	bytes, err := json.Marshal(toBlockElement(a))
+	if err != nil {
+		return nil, err
+	}
+
+	return bytes, nil
+}
+
+// UnmarshalJSON implements the Unmarshaller interface for Accessory, so that any JSON
+// unmarshalling is delegated and proper type determination can be made before unmarshal
+func (a *Accessory) UnmarshalJSON(data []byte) error {
+	var r json.RawMessage
+
+	if string(data) == "{\"accessory\":null}" {
+		return nil
+	}
+
+	err := json.Unmarshal(data, &r)
+	if err != nil {
+		return err
+	}
+
+	s := sumtype{}
+	err = json.Unmarshal(r, &s)
+	if err != nil {
+		return err
+	}
+
+	var blockElementType string
+	if s.TypeVal != "" {
+		blockElementType = s.TypeVal
+	}
+
+	switch blockElementType {
+	case "image":
+		element, err := unmarshalBlockElement(r, &ImageBlockElement{})
+		if err != nil {
+			return err
+		}
+		a.ImageElement = element.(*ImageBlockElement)
+	case "button":
+		element, err := unmarshalBlockElement(r, &ButtonBlockElement{})
+		if err != nil {
+			return err
+		}
+		a.ButtonElement = element.(*ButtonBlockElement)
+	case "overflow":
+		element, err := unmarshalBlockElement(r, &OverflowBlockElement{})
+		if err != nil {
+			return err
+		}
+		a.OverflowElement = element.(*OverflowBlockElement)
+	case "datepicker":
+		element, err := unmarshalBlockElement(r, &DatePickerBlockElement{})
+		if err != nil {
+			return err
+		}
+		a.DatePickerElement = element.(*DatePickerBlockElement)
+	case "static_select":
+		element, err := unmarshalBlockElement(r, &SelectBlockElement{})
+		if err != nil {
+			return err
+		}
+		a.SelectElement = element.(*SelectBlockElement)
+	}
+
+	return nil
+}
+
+func unmarshalBlockElement(r json.RawMessage, element BlockElement) (BlockElement, error) {
+	err := json.Unmarshal(r, element)
+	if err != nil {
+		return nil, err
+	}
+	return element, nil
+}
+
+func toBlockElement(element *Accessory) BlockElement {
+	if element.ImageElement != nil {
+		return element.ImageElement
+	}
+	if element.ButtonElement != nil {
+		return element.ButtonElement
+	}
+	if element.OverflowElement != nil {
+		return element.OverflowElement
+	}
+	if element.DatePickerElement != nil {
+		return element.DatePickerElement
+	}
+	if element.SelectElement != nil {
+		return element.SelectElement
+	}
+
+	return nil
+}
+
+// MarshalJSON implements the Marshaller interface for ContextElements so that any JSON
+// marshalling is delegated and proper type determination can be made before marshal
+func (e *ContextElements) MarshalJSON() ([]byte, error) {
+	bytes, err := json.Marshal(e.Elements)
+	if err != nil {
+		return nil, err
+	}
+
+	return bytes, nil
+}
+
+// UnmarshalJSON implements the Unmarshaller interface for ContextElements, so that any JSON
+// unmarshalling is delegated and proper type determination can be made before unmarshal
+func (e *ContextElements) UnmarshalJSON(data []byte) error {
+	var raw []json.RawMessage
+
+	if string(data) == "{\"elements\":null}" {
+		return nil
+	}
+
+	err := json.Unmarshal(data, &raw)
+	if err != nil {
+		return err
+	}
+
+	for _, r := range raw {
+		s := sumtype{}
+		err := json.Unmarshal(r, &s)
+		if err != nil {
+			return err
+		}
+
+		var contextElementType string
+		if s.TypeVal != "" {
+			contextElementType = s.TypeVal
+		}
+
+		switch contextElementType {
+		case PlainTextType, MarkdownType:
+			elem, err := unmarshalBlockObject(r, &TextBlockObject{})
+			if err != nil {
+				return err
+			}
+
+			e.Elements = append(e.Elements, elem.(*TextBlockObject))
+		case "image":
+			elem, err := unmarshalBlockElement(r, &ImageBlockElement{})
+			if err != nil {
+				return err
+			}
+
+			e.Elements = append(e.Elements, elem.(*ImageBlockElement))
+		default:
+			return errors.New("unsupported context element type")
+		}
+	}
+
+	return nil
+}
diff --git a/vendor/github.com/slack-go/slack/block_divider.go b/vendor/github.com/slack-go/slack/block_divider.go
new file mode 100644
index 00000000..2d442ba1
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/block_divider.go
@@ -0,0 +1,22 @@
+package slack
+
+// DividerBlock for displaying a divider line between blocks (similar to <hr> tag in html)
+//
+// More Information: https://api.slack.com/reference/messaging/blocks#divider
+type DividerBlock struct {
+	Type    MessageBlockType `json:"type"`
+	BlockID string           `json:"block_id,omitempty"`
+}
+
+// BlockType returns the type of the block
+func (s DividerBlock) BlockType() MessageBlockType {
+	return s.Type
+}
+
+// NewDividerBlock returns a new instance of a divider block
+func NewDividerBlock() *DividerBlock {
+	return &DividerBlock{
+		Type: MBTDivider,
+	}
+
+}
diff --git a/vendor/github.com/slack-go/slack/block_element.go b/vendor/github.com/slack-go/slack/block_element.go
new file mode 100644
index 00000000..e0a7bf96
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/block_element.go
@@ -0,0 +1,267 @@
+package slack
+
+// https://api.slack.com/reference/messaging/block-elements
+
+const (
+	METImage          MessageElementType = "image"
+	METButton         MessageElementType = "button"
+	METOverflow       MessageElementType = "overflow"
+	METDatepicker     MessageElementType = "datepicker"
+	METPlainTextInput MessageElementType = "plain_text_input"
+
+	MixedElementImage MixedElementType = "mixed_image"
+	MixedElementText  MixedElementType = "mixed_text"
+
+	OptTypeStatic        string = "static_select"
+	OptTypeExternal      string = "external_select"
+	OptTypeUser          string = "users_select"
+	OptTypeConversations string = "conversations_select"
+	OptTypeChannels      string = "channels_select"
+)
+
+type MessageElementType string
+type MixedElementType string
+
+// BlockElement defines an interface that all block element types should implement.
+type BlockElement interface {
+	ElementType() MessageElementType
+}
+
+type MixedElement interface {
+	MixedElementType() MixedElementType
+}
+
+type Accessory struct {
+	ImageElement      *ImageBlockElement
+	ButtonElement     *ButtonBlockElement
+	OverflowElement   *OverflowBlockElement
+	DatePickerElement *DatePickerBlockElement
+	SelectElement     *SelectBlockElement
+}
+
+// NewAccessory returns a new Accessory for a given block element
+func NewAccessory(element BlockElement) *Accessory {
+	switch element.(type) {
+	case *ImageBlockElement:
+		return &Accessory{ImageElement: element.(*ImageBlockElement)}
+	case *ButtonBlockElement:
+		return &Accessory{ButtonElement: element.(*ButtonBlockElement)}
+	case *OverflowBlockElement:
+		return &Accessory{OverflowElement: element.(*OverflowBlockElement)}
+	case *DatePickerBlockElement:
+		return &Accessory{DatePickerElement: element.(*DatePickerBlockElement)}
+	case *SelectBlockElement:
+		return &Accessory{SelectElement: element.(*SelectBlockElement)}
+	}
+
+	return nil
+}
+
+// BlockElements is a convenience struct defined to allow dynamic unmarshalling of
+// the "elements" value in Slack's JSON response, which varies depending on BlockElement type
+type BlockElements struct {
+	ElementSet []BlockElement `json:"elements,omitempty"`
+}
+
+// ImageBlockElement An element to insert an image - this element can be used
+// in section and context blocks only. If you want a block with only an image
+// in it, you're looking for the image block.
+//
+// More Information: https://api.slack.com/reference/messaging/block-elements#image
+type ImageBlockElement struct {
+	Type     MessageElementType `json:"type"`
+	ImageURL string             `json:"image_url"`
+	AltText  string             `json:"alt_text"`
+}
+
+// ElementType returns the type of the Element
+func (s ImageBlockElement) ElementType() MessageElementType {
+	return s.Type
+}
+
+func (s ImageBlockElement) MixedElementType() MixedElementType {
+	return MixedElementImage
+}
+
+// NewImageBlockElement returns a new instance of an image block element
+func NewImageBlockElement(imageURL, altText string) *ImageBlockElement {
+	return &ImageBlockElement{
+		Type:     METImage,
+		ImageURL: imageURL,
+		AltText:  altText,
+	}
+}
+
+type Style string
+
+const (
+	StyleDefault Style = "default"
+	StylePrimary Style = "primary"
+	StyleDanger  Style = "danger"
+)
+
+// ButtonBlockElement defines an interactive element that inserts a button. The
+// button can be a trigger for anything from opening a simple link to starting
+// a complex workflow.
+//
+// More Information: https://api.slack.com/reference/messaging/block-elements#button
+type ButtonBlockElement struct {
+	Type     MessageElementType       `json:"type,omitempty"`
+	Text     *TextBlockObject         `json:"text"`
+	ActionID string                   `json:"action_id,omitempty"`
+	URL      string                   `json:"url,omitempty"`
+	Value    string                   `json:"value,omitempty"`
+	Confirm  *ConfirmationBlockObject `json:"confirm,omitempty"`
+	Style    Style                    `json:"style,omitempty"`
+}
+
+// ElementType returns the type of the element
+func (s ButtonBlockElement) ElementType() MessageElementType {
+	return s.Type
+}
+
+// add styling to button object
+func (s *ButtonBlockElement) WithStyle(style Style) {
+	s.Style = style
+}
+
+// NewButtonBlockElement returns an instance of a new button element to be used within a block
+func NewButtonBlockElement(actionID, value string, text *TextBlockObject) *ButtonBlockElement {
+	return &ButtonBlockElement{
+		Type:     METButton,
+		ActionID: actionID,
+		Text:     text,
+		Value:    value,
+	}
+}
+
+// SelectBlockElement defines the simplest form of select menu, with a static list
+// of options passed in when defining the element.
+//
+// More Information: https://api.slack.com/reference/messaging/block-elements#select
+type SelectBlockElement struct {
+	Type                string                    `json:"type,omitempty"`
+	Placeholder         *TextBlockObject          `json:"placeholder,omitempty"`
+	ActionID            string                    `json:"action_id,omitempty"`
+	Options             []*OptionBlockObject      `json:"options,omitempty"`
+	OptionGroups        []*OptionGroupBlockObject `json:"option_groups,omitempty"`
+	InitialOption       *OptionBlockObject        `json:"initial_option,omitempty"`
+	InitialUser         string                    `json:"initial_user,omitempty"`
+	InitialConversation string                    `json:"initial_conversation,omitempty"`
+	InitialChannel      string                    `json:"initial_channel,omitempty"`
+	MinQueryLength      int                       `json:"min_query_length,omitempty"`
+	Confirm             *ConfirmationBlockObject  `json:"confirm,omitempty"`
+}
+
+// ElementType returns the type of the Element
+func (s SelectBlockElement) ElementType() MessageElementType {
+	return MessageElementType(s.Type)
+}
+
+// NewOptionsSelectBlockElement returns a new instance of SelectBlockElement for use with
+// the Options object only.
+func NewOptionsSelectBlockElement(optType string, placeholder *TextBlockObject, actionID string, options ...*OptionBlockObject) *SelectBlockElement {
+	return &SelectBlockElement{
+		Type:        optType,
+		Placeholder: placeholder,
+		ActionID:    actionID,
+		Options:     options,
+	}
+}
+
+// NewOptionsGroupSelectBlockElement returns a new instance of SelectBlockElement for use with
+// the Options object only.
+func NewOptionsGroupSelectBlockElement(
+	optType string,
+	placeholder *TextBlockObject,
+	actionID string,
+	optGroups ...*OptionGroupBlockObject,
+) *SelectBlockElement {
+	return &SelectBlockElement{
+		Type:         optType,
+		Placeholder:  placeholder,
+		ActionID:     actionID,
+		OptionGroups: optGroups,
+	}
+}
+
+// OverflowBlockElement defines the fields needed to use an overflow element.
+// And Overflow Element is like a cross between a button and a select menu -
+// when a user clicks on this overflow button, they will be presented with a
+// list of options to choose from.
+//
+// More Information: https://api.slack.com/reference/messaging/block-elements#overflow
+type OverflowBlockElement struct {
+	Type     MessageElementType       `json:"type"`
+	ActionID string                   `json:"action_id,omitempty"`
+	Options  []*OptionBlockObject     `json:"options"`
+	Confirm  *ConfirmationBlockObject `json:"confirm,omitempty"`
+}
+
+// ElementType returns the type of the Element
+func (s OverflowBlockElement) ElementType() MessageElementType {
+	return s.Type
+}
+
+// NewOverflowBlockElement returns an instance of a new Overflow Block Element
+func NewOverflowBlockElement(actionID string, options ...*OptionBlockObject) *OverflowBlockElement {
+	return &OverflowBlockElement{
+		Type:     METOverflow,
+		ActionID: actionID,
+		Options:  options,
+	}
+}
+
+// DatePickerBlockElement defines an element which lets users easily select a
+// date from a calendar style UI. Date picker elements can be used inside of
+// section and actions blocks.
+//
+// More Information: https://api.slack.com/reference/messaging/block-elements#datepicker
+type DatePickerBlockElement struct {
+	Type        MessageElementType       `json:"type"`
+	ActionID    string                   `json:"action_id"`
+	Placeholder *TextBlockObject         `json:"placeholder,omitempty"`
+	InitialDate string                   `json:"initial_date,omitempty"`
+	Confirm     *ConfirmationBlockObject `json:"confirm,omitempty"`
+}
+
+// ElementType returns the type of the Element
+func (s DatePickerBlockElement) ElementType() MessageElementType {
+	return s.Type
+}
+
+// NewDatePickerBlockElement returns an instance of a date picker element
+func NewDatePickerBlockElement(actionID string) *DatePickerBlockElement {
+	return &DatePickerBlockElement{
+		Type:     METDatepicker,
+		ActionID: actionID,
+	}
+}
+
+// PlainTextInputBlockElement creates a field where a user can enter freeform data.
+// Plain-text input elements are currently only available in modals.
+//
+// More Information: https://api.slack.com/reference/messaging/block-elements#input
+type PlainTextInputBlockElement struct {
+	Type         MessageElementType `json:"type"`
+	ActionID     string             `json:"action_id"`
+	Placeholder  *TextBlockObject   `json:"placeholder,omitempty"`
+	InitialValue string             `json:"initial_value,omitempty"`
+	Multiline    bool               `json:"multiline,omitempty"`
+	MinLength    int                `json:"min_length,omitempty"`
+	MaxLength    int                `json:"max_length,omitempty"`
+}
+
+// ElementType returns the type of the Element
+func (s PlainTextInputBlockElement) ElementType() MessageElementType {
+	return s.Type
+}
+
+// NewPlainTextInputBlockElement returns an instance of a plain-text input element
+func NewPlainTextInputBlockElement(placeholder *TextBlockObject, actionID string) *PlainTextInputBlockElement {
+	return &PlainTextInputBlockElement{
+		Type:        METPlainTextInput,
+		ActionID:    actionID,
+		Placeholder: placeholder,
+	}
+}
diff --git a/vendor/github.com/slack-go/slack/block_image.go b/vendor/github.com/slack-go/slack/block_image.go
new file mode 100644
index 00000000..6de3f63a
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/block_image.go
@@ -0,0 +1,28 @@
+package slack
+
+// ImageBlock defines data required to display an image as a block element
+//
+// More Information: https://api.slack.com/reference/messaging/blocks#image
+type ImageBlock struct {
+	Type     MessageBlockType `json:"type"`
+	ImageURL string           `json:"image_url"`
+	AltText  string           `json:"alt_text"`
+	BlockID  string           `json:"block_id,omitempty"`
+	Title    *TextBlockObject `json:"title"`
+}
+
+// BlockType returns the type of the block
+func (s ImageBlock) BlockType() MessageBlockType {
+	return s.Type
+}
+
+// NewImageBlock returns an instance of a new Image Block type
+func NewImageBlock(imageURL, altText, blockID string, title *TextBlockObject) *ImageBlock {
+	return &ImageBlock{
+		Type:     MBTImage,
+		ImageURL: imageURL,
+		AltText:  altText,
+		BlockID:  blockID,
+		Title:    title,
+	}
+}
diff --git a/vendor/github.com/slack-go/slack/block_input.go b/vendor/github.com/slack-go/slack/block_input.go
new file mode 100644
index 00000000..9d082038
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/block_input.go
@@ -0,0 +1,30 @@
+package slack
+
+// InputBlock defines data that is used to collect information from users -
+// it can hold a plain-text input element, a select menu element,
+// a multi-select menu element, or a datepicker.
+//
+// More Information: https://api.slack.com/reference/messaging/blocks#input
+type InputBlock struct {
+	Type     MessageBlockType `json:"type"`
+	BlockID  string           `json:"block_id,omitempty"`
+	Label    *TextBlockObject `json:"label"`
+	Element  BlockElement     `json:"element"`
+	Hint     *TextBlockObject `json:"hint,omitempty"`
+	Optional bool             `json:"optional,omitempty"`
+}
+
+// BlockType returns the type of the block
+func (s InputBlock) BlockType() MessageBlockType {
+	return s.Type
+}
+
+// NewInputBlock returns a new instance of an Input Block
+func NewInputBlock(blockID string, label *TextBlockObject, element BlockElement) *InputBlock {
+	return &InputBlock{
+		Type:    MBTInput,
+		BlockID: blockID,
+		Label:   label,
+		Element: element,
+	}
+}
diff --git a/vendor/github.com/slack-go/slack/block_object.go b/vendor/github.com/slack-go/slack/block_object.go
new file mode 100644
index 00000000..824ec93c
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/block_object.go
@@ -0,0 +1,216 @@
+package slack
+
+import (
+	"encoding/json"
+)
+
+// Block Objects are also known as Composition Objects
+//
+// For more information: https://api.slack.com/reference/messaging/composition-objects
+
+// BlockObject defines an interface that all block object types should
+// implement.
+// @TODO: Is this interface needed?
+
+// blockObject object types
+const (
+	MarkdownType  = "mrkdwn"
+	PlainTextType = "plain_text"
+	// The following objects don't actually have types and their corresponding
+	// const values are just for internal use
+	motConfirmation = "confirm"
+	motOption       = "option"
+	motOptionGroup  = "option_group"
+)
+
+type MessageObjectType string
+
+type blockObject interface {
+	validateType() MessageObjectType
+}
+
+type BlockObjects struct {
+	TextObjects         []*TextBlockObject
+	ConfirmationObjects []*ConfirmationBlockObject
+	OptionObjects       []*OptionBlockObject
+	OptionGroupObjects  []*OptionGroupBlockObject
+}
+
+// UnmarshalJSON implements the Unmarshaller interface for BlockObjects, so that any JSON
+// unmarshalling is delegated and proper type determination can be made before unmarshal
+func (b *BlockObjects) UnmarshalJSON(data []byte) error {
+	var raw []json.RawMessage
+	err := json.Unmarshal(data, &raw)
+	if err != nil {
+		return err
+	}
+
+	for _, r := range raw {
+		var obj map[string]interface{}
+		err := json.Unmarshal(r, &obj)
+		if err != nil {
+			return err
+		}
+
+		blockObjectType := getBlockObjectType(obj)
+
+		switch blockObjectType {
+		case PlainTextType, MarkdownType:
+			object, err := unmarshalBlockObject(r, &TextBlockObject{})
+			if err != nil {
+				return err
+			}
+			b.TextObjects = append(b.TextObjects, object.(*TextBlockObject))
+		case motConfirmation:
+			object, err := unmarshalBlockObject(r, &ConfirmationBlockObject{})
+			if err != nil {
+				return err
+			}
+			b.ConfirmationObjects = append(b.ConfirmationObjects, object.(*ConfirmationBlockObject))
+		case motOption:
+			object, err := unmarshalBlockObject(r, &OptionBlockObject{})
+			if err != nil {
+				return err
+			}
+			b.OptionObjects = append(b.OptionObjects, object.(*OptionBlockObject))
+		case motOptionGroup:
+			object, err := unmarshalBlockObject(r, &OptionGroupBlockObject{})
+			if err != nil {
+				return err
+			}
+			b.OptionGroupObjects = append(b.OptionGroupObjects, object.(*OptionGroupBlockObject))
+
+		}
+	}
+
+	return nil
+}
+
+// Ideally would have a better way to identify the block objects for
+// type casting at time of unmarshalling, should be adapted if possible
+// to accomplish in a more reliable manner.
+func getBlockObjectType(obj map[string]interface{}) string {
+	if t, ok := obj["type"].(string); ok {
+		return t
+	}
+	if _, ok := obj["confirm"].(string); ok {
+		return "confirm"
+	}
+	if _, ok := obj["options"].(string); ok {
+		return "option_group"
+	}
+	if _, ok := obj["text"].(string); ok {
+		if _, ok := obj["value"].(string); ok {
+			return "option"
+		}
+	}
+	return ""
+}
+
+func unmarshalBlockObject(r json.RawMessage, object blockObject) (blockObject, error) {
+	err := json.Unmarshal(r, object)
+	if err != nil {
+		return nil, err
+	}
+	return object, nil
+}
+
+// TextBlockObject defines a text element object to be used with blocks
+//
+// More Information: https://api.slack.com/reference/messaging/composition-objects#text
+type TextBlockObject struct {
+	Type     string `json:"type"`
+	Text     string `json:"text"`
+	Emoji    bool   `json:"emoji,omitempty"`
+	Verbatim bool   `json:"verbatim,omitempty"`
+}
+
+// validateType enforces block objects for element and block parameters
+func (s TextBlockObject) validateType() MessageObjectType {
+	return MessageObjectType(s.Type)
+}
+
+// validateType enforces block objects for element and block parameters
+func (s TextBlockObject) MixedElementType() MixedElementType {
+	return MixedElementText
+}
+
+// NewTextBlockObject returns an instance of a new Text Block Object
+func NewTextBlockObject(elementType, text string, emoji, verbatim bool) *TextBlockObject {
+	return &TextBlockObject{
+		Type:     elementType,
+		Text:     text,
+		Emoji:    emoji,
+		Verbatim: verbatim,
+	}
+}
+
+// ConfirmationBlockObject defines a dialog that provides a confirmation step to
+// any interactive element. This dialog will ask the user to confirm their action by
+// offering a confirm and deny buttons.
+//
+// More Information: https://api.slack.com/reference/messaging/composition-objects#confirm
+type ConfirmationBlockObject struct {
+	Title   *TextBlockObject `json:"title"`
+	Text    *TextBlockObject `json:"text"`
+	Confirm *TextBlockObject `json:"confirm"`
+	Deny    *TextBlockObject `json:"deny"`
+}
+
+// validateType enforces block objects for element and block parameters
+func (s ConfirmationBlockObject) validateType() MessageObjectType {
+	return motConfirmation
+}
+
+// NewConfirmationBlockObject returns an instance of a new Confirmation Block Object
+func NewConfirmationBlockObject(title, text, confirm, deny *TextBlockObject) *ConfirmationBlockObject {
+	return &ConfirmationBlockObject{
+		Title:   title,
+		Text:    text,
+		Confirm: confirm,
+		Deny:    deny,
+	}
+}
+
+// OptionBlockObject represents a single selectable item in a select menu
+//
+// More Information: https://api.slack.com/reference/messaging/composition-objects#option
+type OptionBlockObject struct {
+	Text  *TextBlockObject `json:"text"`
+	Value string           `json:"value"`
+	URL   string           `json:"url,omitempty"`
+}
+
+// NewOptionBlockObject returns an instance of a new Option Block Element
+func NewOptionBlockObject(value string, text *TextBlockObject) *OptionBlockObject {
+	return &OptionBlockObject{
+		Text:  text,
+		Value: value,
+	}
+}
+
+// validateType enforces block objects for element and block parameters
+func (s OptionBlockObject) validateType() MessageObjectType {
+	return motOption
+}
+
+// OptionGroupBlockObject Provides a way to group options in a select menu.
+//
+// More Information: https://api.slack.com/reference/messaging/composition-objects#option-group
+type OptionGroupBlockObject struct {
+	Label   *TextBlockObject     `json:"label,omitempty"`
+	Options []*OptionBlockObject `json:"options"`
+}
+
+// validateType enforces block objects for element and block parameters
+func (s OptionGroupBlockObject) validateType() MessageObjectType {
+	return motOptionGroup
+}
+
+// NewOptionGroupBlockElement returns an instance of a new option group block element
+func NewOptionGroupBlockElement(label *TextBlockObject, options ...*OptionBlockObject) *OptionGroupBlockObject {
+	return &OptionGroupBlockObject{
+		Label:   label,
+		Options: options,
+	}
+}
diff --git a/vendor/github.com/slack-go/slack/block_section.go b/vendor/github.com/slack-go/slack/block_section.go
new file mode 100644
index 00000000..01ffd5a1
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/block_section.go
@@ -0,0 +1,42 @@
+package slack
+
+// SectionBlock defines a new block of type section
+//
+// More Information: https://api.slack.com/reference/messaging/blocks#section
+type SectionBlock struct {
+	Type      MessageBlockType   `json:"type"`
+	Text      *TextBlockObject   `json:"text,omitempty"`
+	BlockID   string             `json:"block_id,omitempty"`
+	Fields    []*TextBlockObject `json:"fields,omitempty"`
+	Accessory *Accessory         `json:"accessory,omitempty"`
+}
+
+// BlockType returns the type of the block
+func (s SectionBlock) BlockType() MessageBlockType {
+	return s.Type
+}
+
+// SectionBlockOption allows configuration of options for a new section block
+type SectionBlockOption func(*SectionBlock)
+
+func SectionBlockOptionBlockID(blockID string) SectionBlockOption {
+	return func(block *SectionBlock) {
+		block.BlockID = blockID
+	}
+}
+
+// NewSectionBlock returns a new instance of a section block to be rendered
+func NewSectionBlock(textObj *TextBlockObject, fields []*TextBlockObject, accessory *Accessory, options ...SectionBlockOption) *SectionBlock {
+	block := SectionBlock{
+		Type:      MBTSection,
+		Text:      textObj,
+		Fields:    fields,
+		Accessory: accessory,
+	}
+
+	for _, option := range options {
+		option(&block)
+	}
+
+	return &block
+}
diff --git a/vendor/github.com/slack-go/slack/bots.go b/vendor/github.com/slack-go/slack/bots.go
new file mode 100644
index 00000000..da21ba0c
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/bots.go
@@ -0,0 +1,58 @@
+package slack
+
+import (
+	"context"
+	"net/url"
+)
+
+// Bot contains information about a bot
+type Bot struct {
+	ID      string   `json:"id"`
+	Name    string   `json:"name"`
+	Deleted bool     `json:"deleted"`
+	UserID  string   `json:"user_id"`
+	AppID   string   `json:"app_id"`
+	Updated JSONTime `json:"updated"`
+	Icons   Icons    `json:"icons"`
+}
+
+type botResponseFull struct {
+	Bot `json:"bot,omitempty"` // GetBotInfo
+	SlackResponse
+}
+
+func (api *Client) botRequest(ctx context.Context, path string, values url.Values) (*botResponseFull, error) {
+	response := &botResponseFull{}
+	err := api.postMethod(ctx, path, values, response)
+	if err != nil {
+		return nil, err
+	}
+
+	if err := response.Err(); err != nil {
+		return nil, err
+	}
+
+	return response, nil
+}
+
+// GetBotInfo will retrieve the complete bot information
+func (api *Client) GetBotInfo(bot string) (*Bot, error) {
+	return api.GetBotInfoContext(context.Background(), bot)
+}
+
+// GetBotInfoContext will retrieve the complete bot information using a custom context
+func (api *Client) GetBotInfoContext(ctx context.Context, bot string) (*Bot, error) {
+	values := url.Values{
+		"token": {api.token},
+	}
+
+	if bot != "" {
+		values.Add("bot", bot)
+	}
+
+	response, err := api.botRequest(ctx, "bots.info", values)
+	if err != nil {
+		return nil, err
+	}
+	return &response.Bot, nil
+}
diff --git a/vendor/github.com/slack-go/slack/channels.go b/vendor/github.com/slack-go/slack/channels.go
new file mode 100644
index 00000000..c99e6655
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/channels.go
@@ -0,0 +1,412 @@
+package slack
+
+import (
+	"context"
+	"net/url"
+	"strconv"
+)
+
+type channelResponseFull struct {
+	Channel      Channel   `json:"channel"`
+	Channels     []Channel `json:"channels"`
+	Purpose      string    `json:"purpose"`
+	Topic        string    `json:"topic"`
+	NotInChannel bool      `json:"not_in_channel"`
+	History
+	SlackResponse
+}
+
+// Channel contains information about the channel
+type Channel struct {
+	GroupConversation
+	IsChannel bool   `json:"is_channel"`
+	IsGeneral bool   `json:"is_general"`
+	IsMember  bool   `json:"is_member"`
+	Locale    string `json:"locale"`
+}
+
+func (api *Client) channelRequest(ctx context.Context, path string, values url.Values) (*channelResponseFull, error) {
+	response := &channelResponseFull{}
+	err := postForm(ctx, api.httpclient, api.endpoint+path, values, response, api)
+	if err != nil {
+		return nil, err
+	}
+
+	return response, response.Err()
+}
+
+type channelsConfig struct {
+	values url.Values
+}
+
+// GetChannelsOption option provided when getting channels.
+type GetChannelsOption func(*channelsConfig) error
+
+// GetChannelsOptionExcludeMembers excludes the members collection from each channel.
+func GetChannelsOptionExcludeMembers() GetChannelsOption {
+	return func(config *channelsConfig) error {
+		config.values.Add("exclude_members", "true")
+		return nil
+	}
+}
+
+// GetChannelsOptionExcludeArchived excludes archived channels from results.
+func GetChannelsOptionExcludeArchived() GetChannelsOption {
+	return func(config *channelsConfig) error {
+		config.values.Add("exclude_archived", "true")
+		return nil
+	}
+}
+
+// ArchiveChannel archives the given channel
+// see https://api.slack.com/methods/channels.archive
+func (api *Client) ArchiveChannel(channelID string) error {
+	return api.ArchiveChannelContext(context.Background(), channelID)
+}
+
+// ArchiveChannelContext archives the given channel with a custom context
+// see https://api.slack.com/methods/channels.archive
+func (api *Client) ArchiveChannelContext(ctx context.Context, channelID string) (err error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channelID},
+	}
+
+	_, err = api.channelRequest(ctx, "channels.archive", values)
+	return err
+}
+
+// UnarchiveChannel unarchives the given channel
+// see https://api.slack.com/methods/channels.unarchive
+func (api *Client) UnarchiveChannel(channelID string) error {
+	return api.UnarchiveChannelContext(context.Background(), channelID)
+}
+
+// UnarchiveChannelContext unarchives the given channel with a custom context
+// see https://api.slack.com/methods/channels.unarchive
+func (api *Client) UnarchiveChannelContext(ctx context.Context, channelID string) (err error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channelID},
+	}
+
+	_, err = api.channelRequest(ctx, "channels.unarchive", values)
+	return err
+}
+
+// CreateChannel creates a channel with the given name and returns a *Channel
+// see https://api.slack.com/methods/channels.create
+func (api *Client) CreateChannel(channelName string) (*Channel, error) {
+	return api.CreateChannelContext(context.Background(), channelName)
+}
+
+// CreateChannelContext creates a channel with the given name and returns a *Channel with a custom context
+// see https://api.slack.com/methods/channels.create
+func (api *Client) CreateChannelContext(ctx context.Context, channelName string) (*Channel, error) {
+	values := url.Values{
+		"token": {api.token},
+		"name":  {channelName},
+	}
+
+	response, err := api.channelRequest(ctx, "channels.create", values)
+	if err != nil {
+		return nil, err
+	}
+	return &response.Channel, nil
+}
+
+// GetChannelHistory retrieves the channel history
+// see https://api.slack.com/methods/channels.history
+func (api *Client) GetChannelHistory(channelID string, params HistoryParameters) (*History, error) {
+	return api.GetChannelHistoryContext(context.Background(), channelID, params)
+}
+
+// GetChannelHistoryContext retrieves the channel history with a custom context
+// see https://api.slack.com/methods/channels.history
+func (api *Client) GetChannelHistoryContext(ctx context.Context, channelID string, params HistoryParameters) (*History, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channelID},
+	}
+	if params.Latest != DEFAULT_HISTORY_LATEST {
+		values.Add("latest", params.Latest)
+	}
+	if params.Oldest != DEFAULT_HISTORY_OLDEST {
+		values.Add("oldest", params.Oldest)
+	}
+	if params.Count != DEFAULT_HISTORY_COUNT {
+		values.Add("count", strconv.Itoa(params.Count))
+	}
+	if params.Inclusive != DEFAULT_HISTORY_INCLUSIVE {
+		if params.Inclusive {
+			values.Add("inclusive", "1")
+		} else {
+			values.Add("inclusive", "0")
+		}
+	}
+
+	if params.Unreads != DEFAULT_HISTORY_UNREADS {
+		if params.Unreads {
+			values.Add("unreads", "1")
+		} else {
+			values.Add("unreads", "0")
+		}
+	}
+
+	response, err := api.channelRequest(ctx, "channels.history", values)
+	if err != nil {
+		return nil, err
+	}
+	return &response.History, nil
+}
+
+// GetChannelInfo retrieves the given channel
+// see https://api.slack.com/methods/channels.info
+func (api *Client) GetChannelInfo(channelID string) (*Channel, error) {
+	return api.GetChannelInfoContext(context.Background(), channelID)
+}
+
+// GetChannelInfoContext retrieves the given channel with a custom context
+// see https://api.slack.com/methods/channels.info
+func (api *Client) GetChannelInfoContext(ctx context.Context, channelID string) (*Channel, error) {
+	values := url.Values{
+		"token":          {api.token},
+		"channel":        {channelID},
+		"include_locale": {strconv.FormatBool(true)},
+	}
+
+	response, err := api.channelRequest(ctx, "channels.info", values)
+	if err != nil {
+		return nil, err
+	}
+	return &response.Channel, nil
+}
+
+// InviteUserToChannel invites a user to a given channel and returns a *Channel
+// see https://api.slack.com/methods/channels.invite
+func (api *Client) InviteUserToChannel(channelID, user string) (*Channel, error) {
+	return api.InviteUserToChannelContext(context.Background(), channelID, user)
+}
+
+// InviteUserToChannelContext invites a user to a given channel and returns a *Channel with a custom context
+// see https://api.slack.com/methods/channels.invite
+func (api *Client) InviteUserToChannelContext(ctx context.Context, channelID, user string) (*Channel, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channelID},
+		"user":    {user},
+	}
+
+	response, err := api.channelRequest(ctx, "channels.invite", values)
+	if err != nil {
+		return nil, err
+	}
+	return &response.Channel, nil
+}
+
+// JoinChannel joins the currently authenticated user to a channel
+// see https://api.slack.com/methods/channels.join
+func (api *Client) JoinChannel(channelName string) (*Channel, error) {
+	return api.JoinChannelContext(context.Background(), channelName)
+}
+
+// JoinChannelContext joins the currently authenticated user to a channel with a custom context
+// see https://api.slack.com/methods/channels.join
+func (api *Client) JoinChannelContext(ctx context.Context, channelName string) (*Channel, error) {
+	values := url.Values{
+		"token": {api.token},
+		"name":  {channelName},
+	}
+
+	response, err := api.channelRequest(ctx, "channels.join", values)
+	if err != nil {
+		return nil, err
+	}
+	return &response.Channel, nil
+}
+
+// LeaveChannel makes the authenticated user leave the given channel
+// see https://api.slack.com/methods/channels.leave
+func (api *Client) LeaveChannel(channelID string) (bool, error) {
+	return api.LeaveChannelContext(context.Background(), channelID)
+}
+
+// LeaveChannelContext makes the authenticated user leave the given channel with a custom context
+// see https://api.slack.com/methods/channels.leave
+func (api *Client) LeaveChannelContext(ctx context.Context, channelID string) (bool, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channelID},
+	}
+
+	response, err := api.channelRequest(ctx, "channels.leave", values)
+	if err != nil {
+		return false, err
+	}
+
+	return response.NotInChannel, nil
+}
+
+// KickUserFromChannel kicks a user from a given channel
+// see https://api.slack.com/methods/channels.kick
+func (api *Client) KickUserFromChannel(channelID, user string) error {
+	return api.KickUserFromChannelContext(context.Background(), channelID, user)
+}
+
+// KickUserFromChannelContext kicks a user from a given channel with a custom context
+// see https://api.slack.com/methods/channels.kick
+func (api *Client) KickUserFromChannelContext(ctx context.Context, channelID, user string) (err error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channelID},
+		"user":    {user},
+	}
+
+	_, err = api.channelRequest(ctx, "channels.kick", values)
+	return err
+}
+
+// GetChannels retrieves all the channels
+// see https://api.slack.com/methods/channels.list
+func (api *Client) GetChannels(excludeArchived bool, options ...GetChannelsOption) ([]Channel, error) {
+	return api.GetChannelsContext(context.Background(), excludeArchived, options...)
+}
+
+// GetChannelsContext retrieves all the channels with a custom context
+// see https://api.slack.com/methods/channels.list
+func (api *Client) GetChannelsContext(ctx context.Context, excludeArchived bool, options ...GetChannelsOption) ([]Channel, error) {
+	config := channelsConfig{
+		values: url.Values{
+			"token": {api.token},
+		},
+	}
+
+	if excludeArchived {
+		options = append(options, GetChannelsOptionExcludeArchived())
+	}
+
+	for _, opt := range options {
+		if err := opt(&config); err != nil {
+			return nil, err
+		}
+	}
+
+	response, err := api.channelRequest(ctx, "channels.list", config.values)
+	if err != nil {
+		return nil, err
+	}
+	return response.Channels, nil
+}
+
+// SetChannelReadMark sets the read mark of a given channel to a specific point
+// Clients should try to avoid making this call too often. When needing to mark a read position, a client should set a
+// timer before making the call. In this way, any further updates needed during the timeout will not generate extra calls
+// (just one per channel). This is useful for when reading scroll-back history, or following a busy live channel. A
+// timeout of 5 seconds is a good starting point. Be sure to flush these calls on shutdown/logout.
+// see https://api.slack.com/methods/channels.mark
+func (api *Client) SetChannelReadMark(channelID, ts string) error {
+	return api.SetChannelReadMarkContext(context.Background(), channelID, ts)
+}
+
+// SetChannelReadMarkContext sets the read mark of a given channel to a specific point with a custom context
+// For more details see SetChannelReadMark documentation
+// see https://api.slack.com/methods/channels.mark
+func (api *Client) SetChannelReadMarkContext(ctx context.Context, channelID, ts string) (err error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channelID},
+		"ts":      {ts},
+	}
+
+	_, err = api.channelRequest(ctx, "channels.mark", values)
+	return err
+}
+
+// RenameChannel renames a given channel
+// see https://api.slack.com/methods/channels.rename
+func (api *Client) RenameChannel(channelID, name string) (*Channel, error) {
+	return api.RenameChannelContext(context.Background(), channelID, name)
+}
+
+// RenameChannelContext renames a given channel with a custom context
+// see https://api.slack.com/methods/channels.rename
+func (api *Client) RenameChannelContext(ctx context.Context, channelID, name string) (*Channel, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channelID},
+		"name":    {name},
+	}
+
+	// XXX: the created entry in this call returns a string instead of a number
+	// so I may have to do some workaround to solve it.
+	response, err := api.channelRequest(ctx, "channels.rename", values)
+	if err != nil {
+		return nil, err
+	}
+	return &response.Channel, nil
+}
+
+// SetChannelPurpose sets the channel purpose and returns the purpose that was successfully set
+// see https://api.slack.com/methods/channels.setPurpose
+func (api *Client) SetChannelPurpose(channelID, purpose string) (string, error) {
+	return api.SetChannelPurposeContext(context.Background(), channelID, purpose)
+}
+
+// SetChannelPurposeContext sets the channel purpose and returns the purpose that was successfully set with a custom context
+// see https://api.slack.com/methods/channels.setPurpose
+func (api *Client) SetChannelPurposeContext(ctx context.Context, channelID, purpose string) (string, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channelID},
+		"purpose": {purpose},
+	}
+
+	response, err := api.channelRequest(ctx, "channels.setPurpose", values)
+	if err != nil {
+		return "", err
+	}
+	return response.Purpose, nil
+}
+
+// SetChannelTopic sets the channel topic and returns the topic that was successfully set
+// see https://api.slack.com/methods/channels.setTopic
+func (api *Client) SetChannelTopic(channelID, topic string) (string, error) {
+	return api.SetChannelTopicContext(context.Background(), channelID, topic)
+}
+
+// SetChannelTopicContext sets the channel topic and returns the topic that was successfully set with a custom context
+// see https://api.slack.com/methods/channels.setTopic
+func (api *Client) SetChannelTopicContext(ctx context.Context, channelID, topic string) (string, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channelID},
+		"topic":   {topic},
+	}
+
+	response, err := api.channelRequest(ctx, "channels.setTopic", values)
+	if err != nil {
+		return "", err
+	}
+	return response.Topic, nil
+}
+
+// GetChannelReplies gets an entire thread (a message plus all the messages in reply to it).
+// see https://api.slack.com/methods/channels.replies
+func (api *Client) GetChannelReplies(channelID, thread_ts string) ([]Message, error) {
+	return api.GetChannelRepliesContext(context.Background(), channelID, thread_ts)
+}
+
+// GetChannelRepliesContext gets an entire thread (a message plus all the messages in reply to it) with a custom context
+// see https://api.slack.com/methods/channels.replies
+func (api *Client) GetChannelRepliesContext(ctx context.Context, channelID, thread_ts string) ([]Message, error) {
+	values := url.Values{
+		"token":     {api.token},
+		"channel":   {channelID},
+		"thread_ts": {thread_ts},
+	}
+	response, err := api.channelRequest(ctx, "channels.replies", values)
+	if err != nil {
+		return nil, err
+	}
+	return response.History.Messages, nil
+}
diff --git a/vendor/github.com/slack-go/slack/chat.go b/vendor/github.com/slack-go/slack/chat.go
new file mode 100644
index 00000000..b54f8d6d
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/chat.go
@@ -0,0 +1,627 @@
+package slack
+
+import (
+	"context"
+	"encoding/json"
+	"net/http"
+	"net/url"
+
+	"github.com/slack-go/slack/slackutilsx"
+)
+
+const (
+	DEFAULT_MESSAGE_USERNAME         = ""
+	DEFAULT_MESSAGE_REPLY_BROADCAST  = false
+	DEFAULT_MESSAGE_ASUSER           = false
+	DEFAULT_MESSAGE_PARSE            = ""
+	DEFAULT_MESSAGE_THREAD_TIMESTAMP = ""
+	DEFAULT_MESSAGE_LINK_NAMES       = 0
+	DEFAULT_MESSAGE_UNFURL_LINKS     = false
+	DEFAULT_MESSAGE_UNFURL_MEDIA     = true
+	DEFAULT_MESSAGE_ICON_URL         = ""
+	DEFAULT_MESSAGE_ICON_EMOJI       = ""
+	DEFAULT_MESSAGE_MARKDOWN         = true
+	DEFAULT_MESSAGE_ESCAPE_TEXT      = true
+)
+
+type chatResponseFull struct {
+	Channel          string `json:"channel"`
+	Timestamp        string `json:"ts"`         //Regular message timestamp
+	MessageTimeStamp string `json:"message_ts"` //Ephemeral message timestamp
+	Text             string `json:"text"`
+	SlackResponse
+}
+
+// getMessageTimestamp will inspect the `chatResponseFull` to ruturn a timestamp value
+// in `chat.postMessage` its under `ts`
+// in `chat.postEphemeral` its under `message_ts`
+func (c chatResponseFull) getMessageTimestamp() string {
+	if len(c.Timestamp) > 0 {
+		return c.Timestamp
+	}
+	return c.MessageTimeStamp
+}
+
+// PostMessageParameters contains all the parameters necessary (including the optional ones) for a PostMessage() request
+type PostMessageParameters struct {
+	Username        string `json:"username"`
+	AsUser          bool   `json:"as_user"`
+	Parse           string `json:"parse"`
+	ThreadTimestamp string `json:"thread_ts"`
+	ReplyBroadcast  bool   `json:"reply_broadcast"`
+	LinkNames       int    `json:"link_names"`
+	UnfurlLinks     bool   `json:"unfurl_links"`
+	UnfurlMedia     bool   `json:"unfurl_media"`
+	IconURL         string `json:"icon_url"`
+	IconEmoji       string `json:"icon_emoji"`
+	Markdown        bool   `json:"mrkdwn,omitempty"`
+	EscapeText      bool   `json:"escape_text"`
+
+	// chat.postEphemeral support
+	Channel string `json:"channel"`
+	User    string `json:"user"`
+}
+
+// NewPostMessageParameters provides an instance of PostMessageParameters with all the sane default values set
+func NewPostMessageParameters() PostMessageParameters {
+	return PostMessageParameters{
+		Username:        DEFAULT_MESSAGE_USERNAME,
+		User:            DEFAULT_MESSAGE_USERNAME,
+		AsUser:          DEFAULT_MESSAGE_ASUSER,
+		Parse:           DEFAULT_MESSAGE_PARSE,
+		ThreadTimestamp: DEFAULT_MESSAGE_THREAD_TIMESTAMP,
+		LinkNames:       DEFAULT_MESSAGE_LINK_NAMES,
+		UnfurlLinks:     DEFAULT_MESSAGE_UNFURL_LINKS,
+		UnfurlMedia:     DEFAULT_MESSAGE_UNFURL_MEDIA,
+		IconURL:         DEFAULT_MESSAGE_ICON_URL,
+		IconEmoji:       DEFAULT_MESSAGE_ICON_EMOJI,
+		Markdown:        DEFAULT_MESSAGE_MARKDOWN,
+		EscapeText:      DEFAULT_MESSAGE_ESCAPE_TEXT,
+	}
+}
+
+// DeleteMessage deletes a message in a channel
+func (api *Client) DeleteMessage(channel, messageTimestamp string) (string, string, error) {
+	respChannel, respTimestamp, _, err := api.SendMessageContext(context.Background(), channel, MsgOptionDelete(messageTimestamp))
+	return respChannel, respTimestamp, err
+}
+
+// DeleteMessageContext deletes a message in a channel with a custom context
+func (api *Client) DeleteMessageContext(ctx context.Context, channel, messageTimestamp string) (string, string, error) {
+	respChannel, respTimestamp, _, err := api.SendMessageContext(ctx, channel, MsgOptionDelete(messageTimestamp))
+	return respChannel, respTimestamp, err
+}
+
+// PostMessage sends a message to a channel.
+// Message is escaped by default according to https://api.slack.com/docs/formatting
+// Use http://davestevens.github.io/slack-message-builder/ to help crafting your message.
+func (api *Client) PostMessage(channelID string, options ...MsgOption) (string, string, error) {
+	respChannel, respTimestamp, _, err := api.SendMessageContext(
+		context.Background(),
+		channelID,
+		MsgOptionPost(),
+		MsgOptionCompose(options...),
+	)
+	return respChannel, respTimestamp, err
+}
+
+// PostMessageContext sends a message to a channel with a custom context
+// For more details, see PostMessage documentation.
+func (api *Client) PostMessageContext(ctx context.Context, channelID string, options ...MsgOption) (string, string, error) {
+	respChannel, respTimestamp, _, err := api.SendMessageContext(
+		ctx,
+		channelID,
+		MsgOptionPost(),
+		MsgOptionCompose(options...),
+	)
+	return respChannel, respTimestamp, err
+}
+
+// PostEphemeral sends an ephemeral message to a user in a channel.
+// Message is escaped by default according to https://api.slack.com/docs/formatting
+// Use http://davestevens.github.io/slack-message-builder/ to help crafting your message.
+func (api *Client) PostEphemeral(channelID, userID string, options ...MsgOption) (string, error) {
+	return api.PostEphemeralContext(
+		context.Background(),
+		channelID,
+		userID,
+		options...,
+	)
+}
+
+// PostEphemeralContext sends an ephemeal message to a user in a channel with a custom context
+// For more details, see PostEphemeral documentation
+func (api *Client) PostEphemeralContext(ctx context.Context, channelID, userID string, options ...MsgOption) (timestamp string, err error) {
+	_, timestamp, _, err = api.SendMessageContext(ctx, channelID, MsgOptionPostEphemeral(userID), MsgOptionCompose(options...))
+	return timestamp, err
+}
+
+// UpdateMessage updates a message in a channel
+func (api *Client) UpdateMessage(channelID, timestamp string, options ...MsgOption) (string, string, string, error) {
+	return api.SendMessageContext(context.Background(), channelID, MsgOptionUpdate(timestamp), MsgOptionCompose(options...))
+}
+
+// UpdateMessageContext updates a message in a channel
+func (api *Client) UpdateMessageContext(ctx context.Context, channelID, timestamp string, options ...MsgOption) (string, string, string, error) {
+	return api.SendMessageContext(ctx, channelID, MsgOptionUpdate(timestamp), MsgOptionCompose(options...))
+}
+
+// UnfurlMessage unfurls a message in a channel
+func (api *Client) UnfurlMessage(channelID, timestamp string, unfurls map[string]Attachment, options ...MsgOption) (string, string, string, error) {
+	return api.SendMessageContext(context.Background(), channelID, MsgOptionUnfurl(timestamp, unfurls), MsgOptionCompose(options...))
+}
+
+// SendMessage more flexible method for configuring messages.
+func (api *Client) SendMessage(channel string, options ...MsgOption) (string, string, string, error) {
+	return api.SendMessageContext(context.Background(), channel, options...)
+}
+
+// SendMessageContext more flexible method for configuring messages with a custom context.
+func (api *Client) SendMessageContext(ctx context.Context, channelID string, options ...MsgOption) (_channel string, _timestamp string, _text string, err error) {
+	var (
+		req      *http.Request
+		parser   func(*chatResponseFull) responseParser
+		response chatResponseFull
+	)
+
+	if req, parser, err = buildSender(api.endpoint, options...).BuildRequest(api.token, channelID); err != nil {
+		return "", "", "", err
+	}
+
+	if err = doPost(ctx, api.httpclient, req, parser(&response), api); err != nil {
+		return "", "", "", err
+	}
+
+	return response.Channel, response.getMessageTimestamp(), response.Text, response.Err()
+}
+
+// UnsafeApplyMsgOptions utility function for debugging/testing chat requests.
+// NOTE: USE AT YOUR OWN RISK: No issues relating to the use of this function
+// will be supported by the library.
+func UnsafeApplyMsgOptions(token, channel, apiurl string, options ...MsgOption) (string, url.Values, error) {
+	config, err := applyMsgOptions(token, channel, apiurl, options...)
+	return config.endpoint, config.values, err
+}
+
+func applyMsgOptions(token, channel, apiurl string, options ...MsgOption) (sendConfig, error) {
+	config := sendConfig{
+		apiurl:   apiurl,
+		endpoint: apiurl + string(chatPostMessage),
+		values: url.Values{
+			"token":   {token},
+			"channel": {channel},
+		},
+	}
+
+	for _, opt := range options {
+		if err := opt(&config); err != nil {
+			return config, err
+		}
+	}
+
+	return config, nil
+}
+
+func buildSender(apiurl string, options ...MsgOption) sendConfig {
+	return sendConfig{
+		apiurl:  apiurl,
+		options: options,
+	}
+}
+
+type sendMode string
+
+const (
+	chatUpdate        sendMode = "chat.update"
+	chatPostMessage   sendMode = "chat.postMessage"
+	chatDelete        sendMode = "chat.delete"
+	chatPostEphemeral sendMode = "chat.postEphemeral"
+	chatResponse      sendMode = "chat.responseURL"
+	chatMeMessage     sendMode = "chat.meMessage"
+	chatUnfurl        sendMode = "chat.unfurl"
+)
+
+type sendConfig struct {
+	apiurl       string
+	options      []MsgOption
+	mode         sendMode
+	endpoint     string
+	values       url.Values
+	attachments  []Attachment
+	blocks       Blocks
+	responseType string
+}
+
+func (t sendConfig) BuildRequest(token, channelID string) (req *http.Request, _ func(*chatResponseFull) responseParser, err error) {
+	if t, err = applyMsgOptions(token, channelID, t.apiurl, t.options...); err != nil {
+		return nil, nil, err
+	}
+
+	switch t.mode {
+	case chatResponse:
+		return responseURLSender{
+			endpoint:     t.endpoint,
+			values:       t.values,
+			attachments:  t.attachments,
+			blocks:       t.blocks,
+			responseType: t.responseType,
+		}.BuildRequest()
+	default:
+		return formSender{endpoint: t.endpoint, values: t.values}.BuildRequest()
+	}
+}
+
+type formSender struct {
+	endpoint string
+	values   url.Values
+}
+
+func (t formSender) BuildRequest() (*http.Request, func(*chatResponseFull) responseParser, error) {
+	req, err := formReq(t.endpoint, t.values)
+	return req, func(resp *chatResponseFull) responseParser {
+		return newJSONParser(resp)
+	}, err
+}
+
+type responseURLSender struct {
+	endpoint     string
+	values       url.Values
+	attachments  []Attachment
+	blocks       Blocks
+	responseType string
+}
+
+func (t responseURLSender) BuildRequest() (*http.Request, func(*chatResponseFull) responseParser, error) {
+	req, err := jsonReq(t.endpoint, Msg{
+		Text:         t.values.Get("text"),
+		Timestamp:    t.values.Get("ts"),
+		Attachments:  t.attachments,
+		Blocks:       t.blocks,
+		ResponseType: t.responseType,
+	})
+	return req, func(resp *chatResponseFull) responseParser {
+		return newContentTypeParser(resp)
+	}, err
+}
+
+// MsgOption option provided when sending a message.
+type MsgOption func(*sendConfig) error
+
+// MsgOptionPost posts a messages, this is the default.
+func MsgOptionPost() MsgOption {
+	return func(config *sendConfig) error {
+		config.endpoint = config.apiurl + string(chatPostMessage)
+		config.values.Del("ts")
+		return nil
+	}
+}
+
+// MsgOptionPostEphemeral - posts an ephemeral message to the provided user.
+func MsgOptionPostEphemeral(userID string) MsgOption {
+	return func(config *sendConfig) error {
+		config.endpoint = config.apiurl + string(chatPostEphemeral)
+		MsgOptionUser(userID)(config)
+		config.values.Del("ts")
+
+		return nil
+	}
+}
+
+// MsgOptionMeMessage posts a "me message" type from the calling user
+func MsgOptionMeMessage() MsgOption {
+	return func(config *sendConfig) error {
+		config.endpoint = config.apiurl + string(chatMeMessage)
+		return nil
+	}
+}
+
+// MsgOptionUpdate updates a message based on the timestamp.
+func MsgOptionUpdate(timestamp string) MsgOption {
+	return func(config *sendConfig) error {
+		config.endpoint = config.apiurl + string(chatUpdate)
+		config.values.Add("ts", timestamp)
+		return nil
+	}
+}
+
+// MsgOptionDelete deletes a message based on the timestamp.
+func MsgOptionDelete(timestamp string) MsgOption {
+	return func(config *sendConfig) error {
+		config.endpoint = config.apiurl + string(chatDelete)
+		config.values.Add("ts", timestamp)
+		return nil
+	}
+}
+
+// MsgOptionUnfurl unfurls a message based on the timestamp.
+func MsgOptionUnfurl(timestamp string, unfurls map[string]Attachment) MsgOption {
+	return func(config *sendConfig) error {
+		config.endpoint = config.apiurl + string(chatUnfurl)
+		config.values.Add("ts", timestamp)
+		unfurlsStr, err := json.Marshal(unfurls)
+		if err == nil {
+			config.values.Add("unfurls", string(unfurlsStr))
+		}
+		return err
+	}
+}
+
+// MsgOptionResponseURL supplies a url to use as the endpoint.
+func MsgOptionResponseURL(url string, responseType string) MsgOption {
+	return func(config *sendConfig) error {
+		config.mode = chatResponse
+		config.endpoint = url
+		config.responseType = responseType
+		config.values.Del("ts")
+		return nil
+	}
+}
+
+// MsgOptionAsUser whether or not to send the message as the user.
+func MsgOptionAsUser(b bool) MsgOption {
+	return func(config *sendConfig) error {
+		if b != DEFAULT_MESSAGE_ASUSER {
+			config.values.Set("as_user", "true")
+		}
+		return nil
+	}
+}
+
+// MsgOptionUser set the user for the message.
+func MsgOptionUser(userID string) MsgOption {
+	return func(config *sendConfig) error {
+		config.values.Set("user", userID)
+		return nil
+	}
+}
+
+// MsgOptionUsername set the username for the message.
+func MsgOptionUsername(username string) MsgOption {
+	return func(config *sendConfig) error {
+		config.values.Set("username", username)
+		return nil
+	}
+}
+
+// MsgOptionText provide the text for the message, optionally escape the provided
+// text.
+func MsgOptionText(text string, escape bool) MsgOption {
+	return func(config *sendConfig) error {
+		if escape {
+			text = slackutilsx.EscapeMessage(text)
+		}
+		config.values.Add("text", text)
+		return nil
+	}
+}
+
+// MsgOptionAttachments provide attachments for the message.
+func MsgOptionAttachments(attachments ...Attachment) MsgOption {
+	return func(config *sendConfig) error {
+		if attachments == nil {
+			return nil
+		}
+
+		config.attachments = attachments
+
+		// FIXME: We are setting the attachments on the message twice: above for
+		// the json version, and below for the html version.  The marshalled bytes
+		// we put into config.values below don't work directly in the Msg version.
+
+		attachmentBytes, err := json.Marshal(attachments)
+		if err == nil {
+			config.values.Set("attachments", string(attachmentBytes))
+		}
+
+		return err
+	}
+}
+
+// MsgOptionBlocks sets blocks for the message
+func MsgOptionBlocks(blocks ...Block) MsgOption {
+	return func(config *sendConfig) error {
+		if blocks == nil {
+			return nil
+		}
+
+		config.blocks.BlockSet = append(config.blocks.BlockSet, blocks...)
+
+		blocks, err := json.Marshal(blocks)
+		if err == nil {
+			config.values.Set("blocks", string(blocks))
+		}
+		return err
+	}
+}
+
+// MsgOptionEnableLinkUnfurl enables link unfurling
+func MsgOptionEnableLinkUnfurl() MsgOption {
+	return func(config *sendConfig) error {
+		config.values.Set("unfurl_links", "true")
+		return nil
+	}
+}
+
+// MsgOptionDisableLinkUnfurl disables link unfurling
+func MsgOptionDisableLinkUnfurl() MsgOption {
+	return func(config *sendConfig) error {
+		config.values.Set("unfurl_links", "false")
+		return nil
+	}
+}
+
+// MsgOptionDisableMediaUnfurl disables media unfurling.
+func MsgOptionDisableMediaUnfurl() MsgOption {
+	return func(config *sendConfig) error {
+		config.values.Set("unfurl_media", "false")
+		return nil
+	}
+}
+
+// MsgOptionDisableMarkdown disables markdown.
+func MsgOptionDisableMarkdown() MsgOption {
+	return func(config *sendConfig) error {
+		config.values.Set("mrkdwn", "false")
+		return nil
+	}
+}
+
+// MsgOptionTS sets the thread TS of the message to enable creating or replying to a thread
+func MsgOptionTS(ts string) MsgOption {
+	return func(config *sendConfig) error {
+		config.values.Set("thread_ts", ts)
+		return nil
+	}
+}
+
+// MsgOptionBroadcast sets reply_broadcast to true
+func MsgOptionBroadcast() MsgOption {
+	return func(config *sendConfig) error {
+		config.values.Set("reply_broadcast", "true")
+		return nil
+	}
+}
+
+// MsgOptionCompose combines multiple options into a single option.
+func MsgOptionCompose(options ...MsgOption) MsgOption {
+	return func(c *sendConfig) error {
+		for _, opt := range options {
+			if err := opt(c); err != nil {
+				return err
+			}
+		}
+		return nil
+	}
+}
+
+// MsgOptionParse set parse option.
+func MsgOptionParse(b bool) MsgOption {
+	return func(c *sendConfig) error {
+		var v string
+		if b {
+			v = "full"
+		} else {
+			v = "none"
+		}
+		c.values.Set("parse", v)
+		return nil
+	}
+}
+
+// MsgOptionIconURL sets an icon URL
+func MsgOptionIconURL(iconURL string) MsgOption {
+	return func(c *sendConfig) error {
+		c.values.Set("icon_url", iconURL)
+		return nil
+	}
+}
+
+// MsgOptionIconEmoji sets an icon emoji
+func MsgOptionIconEmoji(iconEmoji string) MsgOption {
+	return func(c *sendConfig) error {
+		c.values.Set("icon_emoji", iconEmoji)
+		return nil
+	}
+}
+
+// UnsafeMsgOptionEndpoint deliver the message to the specified endpoint.
+// NOTE: USE AT YOUR OWN RISK: No issues relating to the use of this Option
+// will be supported by the library, it is subject to change without notice that
+// may result in compilation errors or runtime behaviour changes.
+func UnsafeMsgOptionEndpoint(endpoint string, update func(url.Values)) MsgOption {
+	return func(config *sendConfig) error {
+		config.endpoint = endpoint
+		update(config.values)
+		return nil
+	}
+}
+
+// MsgOptionPostMessageParameters maintain backwards compatibility.
+func MsgOptionPostMessageParameters(params PostMessageParameters) MsgOption {
+	return func(config *sendConfig) error {
+		if params.Username != DEFAULT_MESSAGE_USERNAME {
+			config.values.Set("username", params.Username)
+		}
+
+		// chat.postEphemeral support
+		if params.User != DEFAULT_MESSAGE_USERNAME {
+			config.values.Set("user", params.User)
+		}
+
+		// never generates an error.
+		MsgOptionAsUser(params.AsUser)(config)
+
+		if params.Parse != DEFAULT_MESSAGE_PARSE {
+			config.values.Set("parse", params.Parse)
+		}
+		if params.LinkNames != DEFAULT_MESSAGE_LINK_NAMES {
+			config.values.Set("link_names", "1")
+		}
+
+		if params.UnfurlLinks != DEFAULT_MESSAGE_UNFURL_LINKS {
+			config.values.Set("unfurl_links", "true")
+		}
+
+		// I want to send a message with explicit `as_user` `true` and `unfurl_links` `false` in request.
+		// Because setting `as_user` to `true` will change the default value for `unfurl_links` to `true` on Slack API side.
+		if params.AsUser != DEFAULT_MESSAGE_ASUSER && params.UnfurlLinks == DEFAULT_MESSAGE_UNFURL_LINKS {
+			config.values.Set("unfurl_links", "false")
+		}
+		if params.UnfurlMedia != DEFAULT_MESSAGE_UNFURL_MEDIA {
+			config.values.Set("unfurl_media", "false")
+		}
+		if params.IconURL != DEFAULT_MESSAGE_ICON_URL {
+			config.values.Set("icon_url", params.IconURL)
+		}
+		if params.IconEmoji != DEFAULT_MESSAGE_ICON_EMOJI {
+			config.values.Set("icon_emoji", params.IconEmoji)
+		}
+		if params.Markdown != DEFAULT_MESSAGE_MARKDOWN {
+			config.values.Set("mrkdwn", "false")
+		}
+
+		if params.ThreadTimestamp != DEFAULT_MESSAGE_THREAD_TIMESTAMP {
+			config.values.Set("thread_ts", params.ThreadTimestamp)
+		}
+		if params.ReplyBroadcast != DEFAULT_MESSAGE_REPLY_BROADCAST {
+			config.values.Set("reply_broadcast", "true")
+		}
+
+		return nil
+	}
+}
+
+// PermalinkParameters are the parameters required to get a permalink to a
+// message. Slack documentation can be found here:
+// https://api.slack.com/methods/chat.getPermalink
+type PermalinkParameters struct {
+	Channel string
+	Ts      string
+}
+
+// GetPermalink returns the permalink for a message. It takes
+// PermalinkParameters and returns a string containing the permalink. It
+// returns an error if unable to retrieve the permalink.
+func (api *Client) GetPermalink(params *PermalinkParameters) (string, error) {
+	return api.GetPermalinkContext(context.Background(), params)
+}
+
+// GetPermalinkContext returns the permalink for a message using a custom context.
+func (api *Client) GetPermalinkContext(ctx context.Context, params *PermalinkParameters) (string, error) {
+	values := url.Values{
+		"token":      {api.token},
+		"channel":    {params.Channel},
+		"message_ts": {params.Ts},
+	}
+
+	response := struct {
+		Channel   string `json:"channel"`
+		Permalink string `json:"permalink"`
+		SlackResponse
+	}{}
+	err := api.getMethod(ctx, "chat.getPermalink", values, &response)
+	if err != nil {
+		return "", err
+	}
+	return response.Permalink, response.Err()
+}
diff --git a/vendor/github.com/slack-go/slack/comment.go b/vendor/github.com/slack-go/slack/comment.go
new file mode 100644
index 00000000..7d1c0d4e
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/comment.go
@@ -0,0 +1,10 @@
+package slack
+
+// Comment contains all the information relative to a comment
+type Comment struct {
+	ID        string   `json:"id,omitempty"`
+	Created   JSONTime `json:"created,omitempty"`
+	Timestamp JSONTime `json:"timestamp,omitempty"`
+	User      string   `json:"user,omitempty"`
+	Comment   string   `json:"comment,omitempty"`
+}
diff --git a/vendor/github.com/slack-go/slack/conversation.go b/vendor/github.com/slack-go/slack/conversation.go
new file mode 100644
index 00000000..1e4a61f1
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/conversation.go
@@ -0,0 +1,620 @@
+package slack
+
+import (
+	"context"
+	"net/url"
+	"strconv"
+	"strings"
+)
+
+// Conversation is the foundation for IM and BaseGroupConversation
+type Conversation struct {
+	ID                 string   `json:"id"`
+	Created            JSONTime `json:"created"`
+	IsOpen             bool     `json:"is_open"`
+	LastRead           string   `json:"last_read,omitempty"`
+	Latest             *Message `json:"latest,omitempty"`
+	UnreadCount        int      `json:"unread_count,omitempty"`
+	UnreadCountDisplay int      `json:"unread_count_display,omitempty"`
+	IsGroup            bool     `json:"is_group"`
+	IsShared           bool     `json:"is_shared"`
+	IsIM               bool     `json:"is_im"`
+	IsExtShared        bool     `json:"is_ext_shared"`
+	IsOrgShared        bool     `json:"is_org_shared"`
+	IsPendingExtShared bool     `json:"is_pending_ext_shared"`
+	IsPrivate          bool     `json:"is_private"`
+	IsMpIM             bool     `json:"is_mpim"`
+	Unlinked           int      `json:"unlinked"`
+	NameNormalized     string   `json:"name_normalized"`
+	NumMembers         int      `json:"num_members"`
+	Priority           float64  `json:"priority"`
+	User               string   `json:"user"`
+
+	// TODO support pending_shared
+	// TODO support previous_names
+}
+
+// GroupConversation is the foundation for Group and Channel
+type GroupConversation struct {
+	Conversation
+	Name       string   `json:"name"`
+	Creator    string   `json:"creator"`
+	IsArchived bool     `json:"is_archived"`
+	Members    []string `json:"members"`
+	Topic      Topic    `json:"topic"`
+	Purpose    Purpose  `json:"purpose"`
+}
+
+// Topic contains information about the topic
+type Topic struct {
+	Value   string   `json:"value"`
+	Creator string   `json:"creator"`
+	LastSet JSONTime `json:"last_set"`
+}
+
+// Purpose contains information about the purpose
+type Purpose struct {
+	Value   string   `json:"value"`
+	Creator string   `json:"creator"`
+	LastSet JSONTime `json:"last_set"`
+}
+
+type GetUsersInConversationParameters struct {
+	ChannelID string
+	Cursor    string
+	Limit     int
+}
+
+type GetConversationsForUserParameters struct {
+	UserID          string
+	Cursor          string
+	Types           []string
+	Limit           int
+	ExcludeArchived bool
+}
+
+type responseMetaData struct {
+	NextCursor string `json:"next_cursor"`
+}
+
+// GetUsersInConversation returns the list of users in a conversation
+func (api *Client) GetUsersInConversation(params *GetUsersInConversationParameters) ([]string, string, error) {
+	return api.GetUsersInConversationContext(context.Background(), params)
+}
+
+// GetUsersInConversationContext returns the list of users in a conversation with a custom context
+func (api *Client) GetUsersInConversationContext(ctx context.Context, params *GetUsersInConversationParameters) ([]string, string, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {params.ChannelID},
+	}
+	if params.Cursor != "" {
+		values.Add("cursor", params.Cursor)
+	}
+	if params.Limit != 0 {
+		values.Add("limit", strconv.Itoa(params.Limit))
+	}
+	response := struct {
+		Members          []string         `json:"members"`
+		ResponseMetaData responseMetaData `json:"response_metadata"`
+		SlackResponse
+	}{}
+
+	err := api.postMethod(ctx, "conversations.members", values, &response)
+	if err != nil {
+		return nil, "", err
+	}
+
+	if err := response.Err(); err != nil {
+		return nil, "", err
+	}
+
+	return response.Members, response.ResponseMetaData.NextCursor, nil
+}
+
+// GetConversationsForUser returns the list conversations for a given user
+func (api *Client) GetConversationsForUser(params *GetConversationsForUserParameters) (channels []Channel, nextCursor string, err error) {
+	return api.GetConversationsForUserContext(context.Background(), params)
+}
+
+// GetConversationsForUserContext returns the list conversations for a given user with a custom context
+func (api *Client) GetConversationsForUserContext(ctx context.Context, params *GetConversationsForUserParameters) (channels []Channel, nextCursor string, err error) {
+	values := url.Values{
+		"token": {api.token},
+	}
+	if params.UserID != "" {
+		values.Add("user", params.UserID)
+	}
+	if params.Cursor != "" {
+		values.Add("cursor", params.Cursor)
+	}
+	if params.Limit != 0 {
+		values.Add("limit", strconv.Itoa(params.Limit))
+	}
+	if params.Types != nil {
+		values.Add("types", strings.Join(params.Types, ","))
+	}
+	if params.ExcludeArchived {
+		values.Add("exclude_archived", "true")
+	}
+	response := struct {
+		Channels         []Channel        `json:"channels"`
+		ResponseMetaData responseMetaData `json:"response_metadata"`
+		SlackResponse
+	}{}
+	err = api.postMethod(ctx, "users.conversations", values, &response)
+	if err != nil {
+		return nil, "", err
+	}
+
+	return response.Channels, response.ResponseMetaData.NextCursor, response.Err()
+}
+
+// ArchiveConversation archives a conversation
+func (api *Client) ArchiveConversation(channelID string) error {
+	return api.ArchiveConversationContext(context.Background(), channelID)
+}
+
+// ArchiveConversationContext archives a conversation with a custom context
+func (api *Client) ArchiveConversationContext(ctx context.Context, channelID string) error {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channelID},
+	}
+
+	response := SlackResponse{}
+	err := api.postMethod(ctx, "conversations.archive", values, &response)
+	if err != nil {
+		return err
+	}
+
+	return response.Err()
+}
+
+// UnArchiveConversation reverses conversation archival
+func (api *Client) UnArchiveConversation(channelID string) error {
+	return api.UnArchiveConversationContext(context.Background(), channelID)
+}
+
+// UnArchiveConversationContext reverses conversation archival with a custom context
+func (api *Client) UnArchiveConversationContext(ctx context.Context, channelID string) error {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channelID},
+	}
+	response := SlackResponse{}
+	err := api.postMethod(ctx, "conversations.unarchive", values, &response)
+	if err != nil {
+		return err
+	}
+
+	return response.Err()
+}
+
+// SetTopicOfConversation sets the topic for a conversation
+func (api *Client) SetTopicOfConversation(channelID, topic string) (*Channel, error) {
+	return api.SetTopicOfConversationContext(context.Background(), channelID, topic)
+}
+
+// SetTopicOfConversationContext sets the topic for a conversation with a custom context
+func (api *Client) SetTopicOfConversationContext(ctx context.Context, channelID, topic string) (*Channel, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channelID},
+		"topic":   {topic},
+	}
+	response := struct {
+		SlackResponse
+		Channel *Channel `json:"channel"`
+	}{}
+	err := api.postMethod(ctx, "conversations.setTopic", values, &response)
+	if err != nil {
+		return nil, err
+	}
+
+	return response.Channel, response.Err()
+}
+
+// SetPurposeOfConversation sets the purpose for a conversation
+func (api *Client) SetPurposeOfConversation(channelID, purpose string) (*Channel, error) {
+	return api.SetPurposeOfConversationContext(context.Background(), channelID, purpose)
+}
+
+// SetPurposeOfConversationContext sets the purpose for a conversation with a custom context
+func (api *Client) SetPurposeOfConversationContext(ctx context.Context, channelID, purpose string) (*Channel, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channelID},
+		"purpose": {purpose},
+	}
+	response := struct {
+		SlackResponse
+		Channel *Channel `json:"channel"`
+	}{}
+
+	err := api.postMethod(ctx, "conversations.setPurpose", values, &response)
+	if err != nil {
+		return nil, err
+	}
+
+	return response.Channel, response.Err()
+}
+
+// RenameConversation renames a conversation
+func (api *Client) RenameConversation(channelID, channelName string) (*Channel, error) {
+	return api.RenameConversationContext(context.Background(), channelID, channelName)
+}
+
+// RenameConversationContext renames a conversation with a custom context
+func (api *Client) RenameConversationContext(ctx context.Context, channelID, channelName string) (*Channel, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channelID},
+		"name":    {channelName},
+	}
+	response := struct {
+		SlackResponse
+		Channel *Channel `json:"channel"`
+	}{}
+
+	err := api.postMethod(ctx, "conversations.rename", values, &response)
+	if err != nil {
+		return nil, err
+	}
+
+	return response.Channel, response.Err()
+}
+
+// InviteUsersToConversation invites users to a channel
+func (api *Client) InviteUsersToConversation(channelID string, users ...string) (*Channel, error) {
+	return api.InviteUsersToConversationContext(context.Background(), channelID, users...)
+}
+
+// InviteUsersToConversationContext invites users to a channel with a custom context
+func (api *Client) InviteUsersToConversationContext(ctx context.Context, channelID string, users ...string) (*Channel, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channelID},
+		"users":   {strings.Join(users, ",")},
+	}
+	response := struct {
+		SlackResponse
+		Channel *Channel `json:"channel"`
+	}{}
+
+	err := api.postMethod(ctx, "conversations.invite", values, &response)
+	if err != nil {
+		return nil, err
+	}
+
+	return response.Channel, response.Err()
+}
+
+// KickUserFromConversation removes a user from a conversation
+func (api *Client) KickUserFromConversation(channelID string, user string) error {
+	return api.KickUserFromConversationContext(context.Background(), channelID, user)
+}
+
+// KickUserFromConversationContext removes a user from a conversation with a custom context
+func (api *Client) KickUserFromConversationContext(ctx context.Context, channelID string, user string) error {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channelID},
+		"user":    {user},
+	}
+
+	response := SlackResponse{}
+	err := api.postMethod(ctx, "conversations.kick", values, &response)
+	if err != nil {
+		return err
+	}
+
+	return response.Err()
+}
+
+// CloseConversation closes a direct message or multi-person direct message
+func (api *Client) CloseConversation(channelID string) (noOp bool, alreadyClosed bool, err error) {
+	return api.CloseConversationContext(context.Background(), channelID)
+}
+
+// CloseConversationContext closes a direct message or multi-person direct message with a custom context
+func (api *Client) CloseConversationContext(ctx context.Context, channelID string) (noOp bool, alreadyClosed bool, err error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channelID},
+	}
+	response := struct {
+		SlackResponse
+		NoOp          bool `json:"no_op"`
+		AlreadyClosed bool `json:"already_closed"`
+	}{}
+
+	err = api.postMethod(ctx, "conversations.close", values, &response)
+	if err != nil {
+		return false, false, err
+	}
+
+	return response.NoOp, response.AlreadyClosed, response.Err()
+}
+
+// CreateConversation initiates a public or private channel-based conversation
+func (api *Client) CreateConversation(channelName string, isPrivate bool) (*Channel, error) {
+	return api.CreateConversationContext(context.Background(), channelName, isPrivate)
+}
+
+// CreateConversationContext initiates a public or private channel-based conversation with a custom context
+func (api *Client) CreateConversationContext(ctx context.Context, channelName string, isPrivate bool) (*Channel, error) {
+	values := url.Values{
+		"token":      {api.token},
+		"name":       {channelName},
+		"is_private": {strconv.FormatBool(isPrivate)},
+	}
+	response, err := api.channelRequest(ctx, "conversations.create", values)
+	if err != nil {
+		return nil, err
+	}
+
+	return &response.Channel, nil
+}
+
+// GetConversationInfo retrieves information about a conversation
+func (api *Client) GetConversationInfo(channelID string, includeLocale bool) (*Channel, error) {
+	return api.GetConversationInfoContext(context.Background(), channelID, includeLocale)
+}
+
+// GetConversationInfoContext retrieves information about a conversation with a custom context
+func (api *Client) GetConversationInfoContext(ctx context.Context, channelID string, includeLocale bool) (*Channel, error) {
+	values := url.Values{
+		"token":          {api.token},
+		"channel":        {channelID},
+		"include_locale": {strconv.FormatBool(includeLocale)},
+	}
+	response, err := api.channelRequest(ctx, "conversations.info", values)
+	if err != nil {
+		return nil, err
+	}
+
+	return &response.Channel, response.Err()
+}
+
+// LeaveConversation leaves a conversation
+func (api *Client) LeaveConversation(channelID string) (bool, error) {
+	return api.LeaveConversationContext(context.Background(), channelID)
+}
+
+// LeaveConversationContext leaves a conversation with a custom context
+func (api *Client) LeaveConversationContext(ctx context.Context, channelID string) (bool, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channelID},
+	}
+
+	response, err := api.channelRequest(ctx, "conversations.leave", values)
+	if err != nil {
+		return false, err
+	}
+
+	return response.NotInChannel, err
+}
+
+type GetConversationRepliesParameters struct {
+	ChannelID string
+	Timestamp string
+	Cursor    string
+	Inclusive bool
+	Latest    string
+	Limit     int
+	Oldest    string
+}
+
+// GetConversationReplies retrieves a thread of messages posted to a conversation
+func (api *Client) GetConversationReplies(params *GetConversationRepliesParameters) (msgs []Message, hasMore bool, nextCursor string, err error) {
+	return api.GetConversationRepliesContext(context.Background(), params)
+}
+
+// GetConversationRepliesContext retrieves a thread of messages posted to a conversation with a custom context
+func (api *Client) GetConversationRepliesContext(ctx context.Context, params *GetConversationRepliesParameters) (msgs []Message, hasMore bool, nextCursor string, err error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {params.ChannelID},
+		"ts":      {params.Timestamp},
+	}
+	if params.Cursor != "" {
+		values.Add("cursor", params.Cursor)
+	}
+	if params.Latest != "" {
+		values.Add("latest", params.Latest)
+	}
+	if params.Limit != 0 {
+		values.Add("limit", strconv.Itoa(params.Limit))
+	}
+	if params.Oldest != "" {
+		values.Add("oldest", params.Oldest)
+	}
+	if params.Inclusive {
+		values.Add("inclusive", "1")
+	} else {
+		values.Add("inclusive", "0")
+	}
+	response := struct {
+		SlackResponse
+		HasMore          bool `json:"has_more"`
+		ResponseMetaData struct {
+			NextCursor string `json:"next_cursor"`
+		} `json:"response_metadata"`
+		Messages []Message `json:"messages"`
+	}{}
+
+	err = api.postMethod(ctx, "conversations.replies", values, &response)
+	if err != nil {
+		return nil, false, "", err
+	}
+
+	return response.Messages, response.HasMore, response.ResponseMetaData.NextCursor, response.Err()
+}
+
+type GetConversationsParameters struct {
+	Cursor          string
+	ExcludeArchived string
+	Limit           int
+	Types           []string
+}
+
+// GetConversations returns the list of channels in a Slack team
+func (api *Client) GetConversations(params *GetConversationsParameters) (channels []Channel, nextCursor string, err error) {
+	return api.GetConversationsContext(context.Background(), params)
+}
+
+// GetConversationsContext returns the list of channels in a Slack team with a custom context
+func (api *Client) GetConversationsContext(ctx context.Context, params *GetConversationsParameters) (channels []Channel, nextCursor string, err error) {
+	values := url.Values{
+		"token":            {api.token},
+		"exclude_archived": {params.ExcludeArchived},
+	}
+	if params.Cursor != "" {
+		values.Add("cursor", params.Cursor)
+	}
+	if params.Limit != 0 {
+		values.Add("limit", strconv.Itoa(params.Limit))
+	}
+	if params.Types != nil {
+		values.Add("types", strings.Join(params.Types, ","))
+	}
+	response := struct {
+		Channels         []Channel        `json:"channels"`
+		ResponseMetaData responseMetaData `json:"response_metadata"`
+		SlackResponse
+	}{}
+
+	err = api.postMethod(ctx, "conversations.list", values, &response)
+	if err != nil {
+		return nil, "", err
+	}
+
+	return response.Channels, response.ResponseMetaData.NextCursor, response.Err()
+}
+
+type OpenConversationParameters struct {
+	ChannelID string
+	ReturnIM  bool
+	Users     []string
+}
+
+// OpenConversation opens or resumes a direct message or multi-person direct message
+func (api *Client) OpenConversation(params *OpenConversationParameters) (*Channel, bool, bool, error) {
+	return api.OpenConversationContext(context.Background(), params)
+}
+
+// OpenConversationContext opens or resumes a direct message or multi-person direct message with a custom context
+func (api *Client) OpenConversationContext(ctx context.Context, params *OpenConversationParameters) (*Channel, bool, bool, error) {
+	values := url.Values{
+		"token":     {api.token},
+		"return_im": {strconv.FormatBool(params.ReturnIM)},
+	}
+	if params.ChannelID != "" {
+		values.Add("channel", params.ChannelID)
+	}
+	if params.Users != nil {
+		values.Add("users", strings.Join(params.Users, ","))
+	}
+	response := struct {
+		Channel     *Channel `json:"channel"`
+		NoOp        bool     `json:"no_op"`
+		AlreadyOpen bool     `json:"already_open"`
+		SlackResponse
+	}{}
+
+	err := api.postMethod(ctx, "conversations.open", values, &response)
+	if err != nil {
+		return nil, false, false, err
+	}
+
+	return response.Channel, response.NoOp, response.AlreadyOpen, response.Err()
+}
+
+// JoinConversation joins an existing conversation
+func (api *Client) JoinConversation(channelID string) (*Channel, string, []string, error) {
+	return api.JoinConversationContext(context.Background(), channelID)
+}
+
+// JoinConversationContext joins an existing conversation with a custom context
+func (api *Client) JoinConversationContext(ctx context.Context, channelID string) (*Channel, string, []string, error) {
+	values := url.Values{"token": {api.token}, "channel": {channelID}}
+	response := struct {
+		Channel          *Channel `json:"channel"`
+		Warning          string   `json:"warning"`
+		ResponseMetaData *struct {
+			Warnings []string `json:"warnings"`
+		} `json:"response_metadata"`
+		SlackResponse
+	}{}
+
+	err := api.postMethod(ctx, "conversations.join", values, &response)
+	if err != nil {
+		return nil, "", nil, err
+	}
+	if response.Err() != nil {
+		return nil, "", nil, response.Err()
+	}
+	var warnings []string
+	if response.ResponseMetaData != nil {
+		warnings = response.ResponseMetaData.Warnings
+	}
+	return response.Channel, response.Warning, warnings, nil
+}
+
+type GetConversationHistoryParameters struct {
+	ChannelID string
+	Cursor    string
+	Inclusive bool
+	Latest    string
+	Limit     int
+	Oldest    string
+}
+
+type GetConversationHistoryResponse struct {
+	SlackResponse
+	HasMore          bool   `json:"has_more"`
+	PinCount         int    `json:"pin_count"`
+	Latest           string `json:"latest"`
+	ResponseMetaData struct {
+		NextCursor string `json:"next_cursor"`
+	} `json:"response_metadata"`
+	Messages []Message `json:"messages"`
+}
+
+// GetConversationHistory joins an existing conversation
+func (api *Client) GetConversationHistory(params *GetConversationHistoryParameters) (*GetConversationHistoryResponse, error) {
+	return api.GetConversationHistoryContext(context.Background(), params)
+}
+
+// GetConversationHistoryContext joins an existing conversation with a custom context
+func (api *Client) GetConversationHistoryContext(ctx context.Context, params *GetConversationHistoryParameters) (*GetConversationHistoryResponse, error) {
+	values := url.Values{"token": {api.token}, "channel": {params.ChannelID}}
+	if params.Cursor != "" {
+		values.Add("cursor", params.Cursor)
+	}
+	if params.Inclusive {
+		values.Add("inclusive", "1")
+	} else {
+		values.Add("inclusive", "0")
+	}
+	if params.Latest != "" {
+		values.Add("latest", params.Latest)
+	}
+	if params.Limit != 0 {
+		values.Add("limit", strconv.Itoa(params.Limit))
+	}
+	if params.Oldest != "" {
+		values.Add("oldest", params.Oldest)
+	}
+
+	response := GetConversationHistoryResponse{}
+
+	err := api.postMethod(ctx, "conversations.history", values, &response)
+	if err != nil {
+		return nil, err
+	}
+
+	return &response, response.Err()
+}
diff --git a/vendor/github.com/slack-go/slack/dialog.go b/vendor/github.com/slack-go/slack/dialog.go
new file mode 100644
index 00000000..376cd9e6
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/dialog.go
@@ -0,0 +1,118 @@
+package slack
+
+import (
+	"context"
+	"encoding/json"
+	"strings"
+)
+
+// InputType is the type of the dialog input type
+type InputType string
+
+const (
+	// InputTypeText textfield input
+	InputTypeText InputType = "text"
+	// InputTypeTextArea textarea input
+	InputTypeTextArea InputType = "textarea"
+	// InputTypeSelect select menus input
+	InputTypeSelect InputType = "select"
+)
+
+// DialogInput for dialogs input type text or menu
+type DialogInput struct {
+	Type        InputType `json:"type"`
+	Label       string    `json:"label"`
+	Name        string    `json:"name"`
+	Placeholder string    `json:"placeholder"`
+	Optional    bool      `json:"optional"`
+	Hint        string    `json:"hint"`
+}
+
+// DialogTrigger ...
+type DialogTrigger struct {
+	TriggerID string `json:"trigger_id"` //Required. Must respond within 3 seconds.
+	Dialog    Dialog `json:"dialog"`     //Required.
+}
+
+// Dialog as in Slack dialogs
+// https://api.slack.com/dialogs#option_element_attributes#top-level_dialog_attributes
+type Dialog struct {
+	TriggerID      string          `json:"trigger_id"`      // Required
+	CallbackID     string          `json:"callback_id"`     // Required
+	State          string          `json:"state,omitempty"` // Optional
+	Title          string          `json:"title"`
+	SubmitLabel    string          `json:"submit_label,omitempty"`
+	NotifyOnCancel bool            `json:"notify_on_cancel"`
+	Elements       []DialogElement `json:"elements"`
+}
+
+// DialogElement abstract type for dialogs.
+type DialogElement interface{}
+
+// DialogCallback DEPRECATED use InteractionCallback
+type DialogCallback InteractionCallback
+
+// DialogSubmissionCallback is sent from Slack when a user submits a form from within a dialog
+type DialogSubmissionCallback struct {
+	State      string            `json:"state,omitempty"`
+	Submission map[string]string `json:"submission"`
+}
+
+// DialogOpenResponse response from `dialog.open`
+type DialogOpenResponse struct {
+	SlackResponse
+	DialogResponseMetadata DialogResponseMetadata `json:"response_metadata"`
+}
+
+// DialogResponseMetadata lists the error messages
+type DialogResponseMetadata struct {
+	Messages []string `json:"messages"`
+}
+
+// DialogInputValidationError is an error when user inputs incorrect value to form from within a dialog
+type DialogInputValidationError struct {
+	Name  string `json:"name"`
+	Error string `json:"error"`
+}
+
+// DialogInputValidationErrors lists the name of field and that error messages
+type DialogInputValidationErrors struct {
+	Errors []DialogInputValidationError `json:"errors"`
+}
+
+// OpenDialog opens a dialog window where the triggerID originated from.
+// EXPERIMENTAL: dialog functionality is currently experimental, api is not considered stable.
+func (api *Client) OpenDialog(triggerID string, dialog Dialog) (err error) {
+	return api.OpenDialogContext(context.Background(), triggerID, dialog)
+}
+
+// OpenDialogContext opens a dialog window where the triggerId originated from with a custom context
+// EXPERIMENTAL: dialog functionality is currently experimental, api is not considered stable.
+func (api *Client) OpenDialogContext(ctx context.Context, triggerID string, dialog Dialog) (err error) {
+	if triggerID == "" {
+		return ErrParametersMissing
+	}
+
+	req := DialogTrigger{
+		TriggerID: triggerID,
+		Dialog:    dialog,
+	}
+
+	encoded, err := json.Marshal(req)
+	if err != nil {
+		return err
+	}
+
+	response := &DialogOpenResponse{}
+	endpoint := api.endpoint + "dialog.open"
+	if err := postJSON(ctx, api.httpclient, endpoint, api.token, encoded, response, api); err != nil {
+		return err
+	}
+
+	if len(response.DialogResponseMetadata.Messages) > 0 {
+		response.Ok = false
+		response.Error += "\n" + strings.Join(response.DialogResponseMetadata.Messages, "\n")
+	}
+
+	return response.Err()
+}
diff --git a/vendor/github.com/slack-go/slack/dialog_select.go b/vendor/github.com/slack-go/slack/dialog_select.go
new file mode 100644
index 00000000..385cef68
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/dialog_select.go
@@ -0,0 +1,101 @@
+package slack
+
+// SelectDataSource types of select datasource
+type SelectDataSource string
+
+const (
+	// DialogDataSourceStatic menu with static Options/OptionGroups
+	DialogDataSourceStatic SelectDataSource = "static"
+	// DialogDataSourceExternal dynamic datasource
+	DialogDataSourceExternal SelectDataSource = "external"
+	// DialogDataSourceConversations provides a list of conversations
+	DialogDataSourceConversations SelectDataSource = "conversations"
+	// DialogDataSourceChannels provides a list of channels
+	DialogDataSourceChannels SelectDataSource = "channels"
+	// DialogDataSourceUsers provides a list of users
+	DialogDataSourceUsers SelectDataSource = "users"
+)
+
+// DialogInputSelect dialog support for select boxes.
+type DialogInputSelect struct {
+	DialogInput
+	Value           string               `json:"value,omitempty"`            //Optional.
+	DataSource      SelectDataSource     `json:"data_source,omitempty"`      //Optional. Allowed values: "users", "channels", "conversations", "external".
+	SelectedOptions []DialogSelectOption `json:"selected_options,omitempty"` //Optional. May hold at most one element, for use with "external" only.
+	Options         []DialogSelectOption `json:"options,omitempty"`          //One of options or option_groups is required.
+	OptionGroups    []DialogOptionGroup  `json:"option_groups,omitempty"`    //Provide up to 100 options.
+	MinQueryLength  int                  `json:"min_query_length,omitempty"` //Optional. minimum characters before query is sent.
+	Hint            string               `json:"hint,omitempty"`             //Optional. Additional hint text.
+}
+
+// DialogSelectOption is an option for the user to select from the menu
+type DialogSelectOption struct {
+	Label string `json:"label"`
+	Value string `json:"value"`
+}
+
+// DialogOptionGroup is a collection of options for creating a segmented table
+type DialogOptionGroup struct {
+	Label   string               `json:"label"`
+	Options []DialogSelectOption `json:"options"`
+}
+
+// NewStaticSelectDialogInput constructor for a `static` datasource menu input
+func NewStaticSelectDialogInput(name, label string, options []DialogSelectOption) *DialogInputSelect {
+	return &DialogInputSelect{
+		DialogInput: DialogInput{
+			Type:     InputTypeSelect,
+			Name:     name,
+			Label:    label,
+			Optional: true,
+		},
+		DataSource: DialogDataSourceStatic,
+		Options:    options,
+	}
+}
+
+// NewGroupedSelectDialogInput creates grouped options select input for Dialogs.
+func NewGroupedSelectDialogInput(name, label string, options []DialogOptionGroup) *DialogInputSelect {
+	return &DialogInputSelect{
+		DialogInput: DialogInput{
+			Type:  InputTypeSelect,
+			Name:  name,
+			Label: label,
+		},
+		DataSource:   DialogDataSourceStatic,
+		OptionGroups: options}
+}
+
+// NewDialogOptionGroup creates a DialogOptionGroup from several select options
+func NewDialogOptionGroup(label string, options ...DialogSelectOption) DialogOptionGroup {
+	return DialogOptionGroup{
+		Label:   label,
+		Options: options,
+	}
+}
+
+// NewConversationsSelect returns a `Conversations` select
+func NewConversationsSelect(name, label string) *DialogInputSelect {
+	return newPresetSelect(name, label, DialogDataSourceConversations)
+}
+
+// NewChannelsSelect returns a `Channels` select
+func NewChannelsSelect(name, label string) *DialogInputSelect {
+	return newPresetSelect(name, label, DialogDataSourceChannels)
+}
+
+// NewUsersSelect returns a `Users` select
+func NewUsersSelect(name, label string) *DialogInputSelect {
+	return newPresetSelect(name, label, DialogDataSourceUsers)
+}
+
+func newPresetSelect(name, label string, dataSourceType SelectDataSource) *DialogInputSelect {
+	return &DialogInputSelect{
+		DialogInput: DialogInput{
+			Type:  InputTypeSelect,
+			Label: label,
+			Name:  name,
+		},
+		DataSource: dataSourceType,
+	}
+}
diff --git a/vendor/github.com/slack-go/slack/dialog_text.go b/vendor/github.com/slack-go/slack/dialog_text.go
new file mode 100644
index 00000000..da06bd6d
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/dialog_text.go
@@ -0,0 +1,59 @@
+package slack
+
+// TextInputSubtype Accepts email, number, tel, or url. In some form factors, optimized input is provided for this subtype.
+type TextInputSubtype string
+
+// TextInputOption handle to extra inputs options.
+type TextInputOption func(*TextInputElement)
+
+const (
+	// InputSubtypeEmail email keyboard
+	InputSubtypeEmail TextInputSubtype = "email"
+	// InputSubtypeNumber numeric keyboard
+	InputSubtypeNumber TextInputSubtype = "number"
+	// InputSubtypeTel Phone keyboard
+	InputSubtypeTel TextInputSubtype = "tel"
+	// InputSubtypeURL Phone keyboard
+	InputSubtypeURL TextInputSubtype = "url"
+)
+
+// TextInputElement subtype of DialogInput
+//	https://api.slack.com/dialogs#option_element_attributes#text_element_attributes
+type TextInputElement struct {
+	DialogInput
+	MaxLength int              `json:"max_length,omitempty"`
+	MinLength int              `json:"min_length,omitempty"`
+	Hint      string           `json:"hint,omitempty"`
+	Subtype   TextInputSubtype `json:"subtype"`
+	Value     string           `json:"value"`
+}
+
+// NewTextInput constructor for a `text` input
+func NewTextInput(name, label, text string, options ...TextInputOption) *TextInputElement {
+	t := &TextInputElement{
+		DialogInput: DialogInput{
+			Type:  InputTypeText,
+			Name:  name,
+			Label: label,
+		},
+		Value: text,
+	}
+
+	for _, opt := range options {
+		opt(t)
+	}
+
+	return t
+}
+
+// NewTextAreaInput constructor for a `textarea` input
+func NewTextAreaInput(name, label, text string) *TextInputElement {
+	return &TextInputElement{
+		DialogInput: DialogInput{
+			Type:  InputTypeTextArea,
+			Name:  name,
+			Label: label,
+		},
+		Value: text,
+	}
+}
diff --git a/vendor/github.com/slack-go/slack/dnd.go b/vendor/github.com/slack-go/slack/dnd.go
new file mode 100644
index 00000000..a3aa680c
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/dnd.go
@@ -0,0 +1,151 @@
+package slack
+
+import (
+	"context"
+	"net/url"
+	"strconv"
+	"strings"
+)
+
+type SnoozeDebug struct {
+	SnoozeEndDate string `json:"snooze_end_date"`
+}
+
+type SnoozeInfo struct {
+	SnoozeEnabled   bool        `json:"snooze_enabled,omitempty"`
+	SnoozeEndTime   int         `json:"snooze_endtime,omitempty"`
+	SnoozeRemaining int         `json:"snooze_remaining,omitempty"`
+	SnoozeDebug     SnoozeDebug `json:"snooze_debug,omitempty"`
+}
+
+type DNDStatus struct {
+	Enabled            bool `json:"dnd_enabled"`
+	NextStartTimestamp int  `json:"next_dnd_start_ts"`
+	NextEndTimestamp   int  `json:"next_dnd_end_ts"`
+	SnoozeInfo
+}
+
+type dndResponseFull struct {
+	DNDStatus
+	SlackResponse
+}
+
+type dndTeamInfoResponse struct {
+	Users map[string]DNDStatus `json:"users"`
+	SlackResponse
+}
+
+func (api *Client) dndRequest(ctx context.Context, path string, values url.Values) (*dndResponseFull, error) {
+	response := &dndResponseFull{}
+	err := api.postMethod(ctx, path, values, response)
+	if err != nil {
+		return nil, err
+	}
+
+	return response, response.Err()
+}
+
+// EndDND ends the user's scheduled Do Not Disturb session
+func (api *Client) EndDND() error {
+	return api.EndDNDContext(context.Background())
+}
+
+// EndDNDContext ends the user's scheduled Do Not Disturb session with a custom context
+func (api *Client) EndDNDContext(ctx context.Context) error {
+	values := url.Values{
+		"token": {api.token},
+	}
+
+	response := &SlackResponse{}
+
+	if err := api.postMethod(ctx, "dnd.endDnd", values, response); err != nil {
+		return err
+	}
+
+	return response.Err()
+}
+
+// EndSnooze ends the current user's snooze mode
+func (api *Client) EndSnooze() (*DNDStatus, error) {
+	return api.EndSnoozeContext(context.Background())
+}
+
+// EndSnoozeContext ends the current user's snooze mode with a custom context
+func (api *Client) EndSnoozeContext(ctx context.Context) (*DNDStatus, error) {
+	values := url.Values{
+		"token": {api.token},
+	}
+
+	response, err := api.dndRequest(ctx, "dnd.endSnooze", values)
+	if err != nil {
+		return nil, err
+	}
+	return &response.DNDStatus, nil
+}
+
+// GetDNDInfo provides information about a user's current Do Not Disturb settings.
+func (api *Client) GetDNDInfo(user *string) (*DNDStatus, error) {
+	return api.GetDNDInfoContext(context.Background(), user)
+}
+
+// GetDNDInfoContext provides information about a user's current Do Not Disturb settings with a custom context.
+func (api *Client) GetDNDInfoContext(ctx context.Context, user *string) (*DNDStatus, error) {
+	values := url.Values{
+		"token": {api.token},
+	}
+	if user != nil {
+		values.Set("user", *user)
+	}
+
+	response, err := api.dndRequest(ctx, "dnd.info", values)
+	if err != nil {
+		return nil, err
+	}
+	return &response.DNDStatus, nil
+}
+
+// GetDNDTeamInfo provides information about a user's current Do Not Disturb settings.
+func (api *Client) GetDNDTeamInfo(users []string) (map[string]DNDStatus, error) {
+	return api.GetDNDTeamInfoContext(context.Background(), users)
+}
+
+// GetDNDTeamInfoContext provides information about a user's current Do Not Disturb settings with a custom context.
+func (api *Client) GetDNDTeamInfoContext(ctx context.Context, users []string) (map[string]DNDStatus, error) {
+	values := url.Values{
+		"token": {api.token},
+		"users": {strings.Join(users, ",")},
+	}
+	response := &dndTeamInfoResponse{}
+
+	if err := api.postMethod(ctx, "dnd.teamInfo", values, response); err != nil {
+		return nil, err
+	}
+
+	if response.Err() != nil {
+		return nil, response.Err()
+	}
+
+	return response.Users, nil
+}
+
+// SetSnooze adjusts the snooze duration for a user's Do Not Disturb
+// settings. If a snooze session is not already active for the user, invoking
+// this method will begin one for the specified duration.
+func (api *Client) SetSnooze(minutes int) (*DNDStatus, error) {
+	return api.SetSnoozeContext(context.Background(), minutes)
+}
+
+// SetSnoozeContext adjusts the snooze duration for a user's Do Not Disturb settings with a custom context.
+// For more information see the SetSnooze docs
+func (api *Client) SetSnoozeContext(ctx context.Context, minutes int) (*DNDStatus, error) {
+	values := url.Values{
+		"token":       {api.token},
+		"num_minutes": {strconv.Itoa(minutes)},
+	}
+
+	response, err := api.dndRequest(ctx, "dnd.setSnooze", values)
+	if err != nil {
+		return nil, err
+	}
+	return &response.DNDStatus, nil
+}
diff --git a/vendor/github.com/slack-go/slack/emoji.go b/vendor/github.com/slack-go/slack/emoji.go
new file mode 100644
index 00000000..b2b0c6c9
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/emoji.go
@@ -0,0 +1,35 @@
+package slack
+
+import (
+	"context"
+	"net/url"
+)
+
+type emojiResponseFull struct {
+	Emoji map[string]string `json:"emoji"`
+	SlackResponse
+}
+
+// GetEmoji retrieves all the emojis
+func (api *Client) GetEmoji() (map[string]string, error) {
+	return api.GetEmojiContext(context.Background())
+}
+
+// GetEmojiContext retrieves all the emojis with a custom context
+func (api *Client) GetEmojiContext(ctx context.Context) (map[string]string, error) {
+	values := url.Values{
+		"token": {api.token},
+	}
+	response := &emojiResponseFull{}
+
+	err := api.postMethod(ctx, "emoji.list", values, response)
+	if err != nil {
+		return nil, err
+	}
+
+	if response.Err() != nil {
+		return nil, response.Err()
+	}
+
+	return response.Emoji, nil
+}
diff --git a/vendor/github.com/slack-go/slack/errors.go b/vendor/github.com/slack-go/slack/errors.go
new file mode 100644
index 00000000..a1dfec25
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/errors.go
@@ -0,0 +1,20 @@
+package slack
+
+import "github.com/slack-go/slack/internal/errorsx"
+
+// Errors returned by various methods.
+const (
+	ErrAlreadyDisconnected  = errorsx.String("Invalid call to Disconnect - Slack API is already disconnected")
+	ErrRTMDisconnected      = errorsx.String("disconnect received while trying to connect")
+	ErrRTMGoodbye           = errorsx.String("goodbye detected")
+	ErrRTMDeadman           = errorsx.String("deadman switch triggered")
+	ErrParametersMissing    = errorsx.String("received empty parameters")
+	ErrInvalidConfiguration = errorsx.String("invalid configuration")
+	ErrMissingHeaders       = errorsx.String("missing headers")
+	ErrExpiredTimestamp     = errorsx.String("timestamp is too old")
+)
+
+// internal errors
+const (
+	errPaginationComplete = errorsx.String("pagination complete")
+)
diff --git a/vendor/github.com/slack-go/slack/files.go b/vendor/github.com/slack-go/slack/files.go
new file mode 100644
index 00000000..3a7363de
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/files.go
@@ -0,0 +1,404 @@
+package slack
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"net/url"
+	"strconv"
+	"strings"
+)
+
+const (
+	// Add here the defaults in the siten
+	DEFAULT_FILES_USER    = ""
+	DEFAULT_FILES_CHANNEL = ""
+	DEFAULT_FILES_TS_FROM = 0
+	DEFAULT_FILES_TS_TO   = -1
+	DEFAULT_FILES_TYPES   = "all"
+	DEFAULT_FILES_COUNT   = 100
+	DEFAULT_FILES_PAGE    = 1
+)
+
+// File contains all the information for a file
+type File struct {
+	ID        string   `json:"id"`
+	Created   JSONTime `json:"created"`
+	Timestamp JSONTime `json:"timestamp"`
+
+	Name              string `json:"name"`
+	Title             string `json:"title"`
+	Mimetype          string `json:"mimetype"`
+	ImageExifRotation int    `json:"image_exif_rotation"`
+	Filetype          string `json:"filetype"`
+	PrettyType        string `json:"pretty_type"`
+	User              string `json:"user"`
+
+	Mode         string `json:"mode"`
+	Editable     bool   `json:"editable"`
+	IsExternal   bool   `json:"is_external"`
+	ExternalType string `json:"external_type"`
+
+	Size int `json:"size"`
+
+	URL                string `json:"url"`          // Deprecated - never set
+	URLDownload        string `json:"url_download"` // Deprecated - never set
+	URLPrivate         string `json:"url_private"`
+	URLPrivateDownload string `json:"url_private_download"`
+
+	OriginalH   int    `json:"original_h"`
+	OriginalW   int    `json:"original_w"`
+	Thumb64     string `json:"thumb_64"`
+	Thumb80     string `json:"thumb_80"`
+	Thumb160    string `json:"thumb_160"`
+	Thumb360    string `json:"thumb_360"`
+	Thumb360Gif string `json:"thumb_360_gif"`
+	Thumb360W   int    `json:"thumb_360_w"`
+	Thumb360H   int    `json:"thumb_360_h"`
+	Thumb480    string `json:"thumb_480"`
+	Thumb480W   int    `json:"thumb_480_w"`
+	Thumb480H   int    `json:"thumb_480_h"`
+	Thumb720    string `json:"thumb_720"`
+	Thumb720W   int    `json:"thumb_720_w"`
+	Thumb720H   int    `json:"thumb_720_h"`
+	Thumb960    string `json:"thumb_960"`
+	Thumb960W   int    `json:"thumb_960_w"`
+	Thumb960H   int    `json:"thumb_960_h"`
+	Thumb1024   string `json:"thumb_1024"`
+	Thumb1024W  int    `json:"thumb_1024_w"`
+	Thumb1024H  int    `json:"thumb_1024_h"`
+
+	Permalink       string `json:"permalink"`
+	PermalinkPublic string `json:"permalink_public"`
+
+	EditLink         string `json:"edit_link"`
+	Preview          string `json:"preview"`
+	PreviewHighlight string `json:"preview_highlight"`
+	Lines            int    `json:"lines"`
+	LinesMore        int    `json:"lines_more"`
+
+	IsPublic        bool     `json:"is_public"`
+	PublicURLShared bool     `json:"public_url_shared"`
+	Channels        []string `json:"channels"`
+	Groups          []string `json:"groups"`
+	IMs             []string `json:"ims"`
+	InitialComment  Comment  `json:"initial_comment"`
+	CommentsCount   int      `json:"comments_count"`
+	NumStars        int      `json:"num_stars"`
+	IsStarred       bool     `json:"is_starred"`
+	Shares          Share    `json:"shares"`
+}
+
+type Share struct {
+	Public  map[string][]ShareFileInfo `json:"public"`
+	Private map[string][]ShareFileInfo `json:"private"`
+}
+
+type ShareFileInfo struct {
+	ReplyUsers      []string `json:"reply_users"`
+	ReplyUsersCount int      `json:"reply_users_count"`
+	ReplyCount      int      `json:"reply_count"`
+	Ts              string   `json:"ts"`
+	ThreadTs        string   `json:"thread_ts"`
+	LatestReply     string   `json:"latest_reply"`
+	ChannelName     string   `json:"channel_name"`
+	TeamID          string   `json:"team_id"`
+}
+
+// FileUploadParameters contains all the parameters necessary (including the optional ones) for an UploadFile() request.
+//
+// There are three ways to upload a file. You can either set Content if file is small, set Reader if file is large,
+// or provide a local file path in File to upload it from your filesystem.
+//
+// Note that when using the Reader option, you *must* specify the Filename, otherwise the Slack API isn't happy.
+type FileUploadParameters struct {
+	File            string
+	Content         string
+	Reader          io.Reader
+	Filetype        string
+	Filename        string
+	Title           string
+	InitialComment  string
+	Channels        []string
+	ThreadTimestamp string
+}
+
+// GetFilesParameters contains all the parameters necessary (including the optional ones) for a GetFiles() request
+type GetFilesParameters struct {
+	User          string
+	Channel       string
+	TimestampFrom JSONTime
+	TimestampTo   JSONTime
+	Types         string
+	Count         int
+	Page          int
+}
+
+// ListFilesParameters contains all the parameters necessary (including the optional ones) for a ListFiles() request
+type ListFilesParameters struct {
+	Limit   int
+	User    string
+	Channel string
+	Types   string
+	Cursor  string
+}
+
+type fileResponseFull struct {
+	File     `json:"file"`
+	Paging   `json:"paging"`
+	Comments []Comment        `json:"comments"`
+	Files    []File           `json:"files"`
+	Metadata ResponseMetadata `json:"response_metadata"`
+
+	SlackResponse
+}
+
+// NewGetFilesParameters provides an instance of GetFilesParameters with all the sane default values set
+func NewGetFilesParameters() GetFilesParameters {
+	return GetFilesParameters{
+		User:          DEFAULT_FILES_USER,
+		Channel:       DEFAULT_FILES_CHANNEL,
+		TimestampFrom: DEFAULT_FILES_TS_FROM,
+		TimestampTo:   DEFAULT_FILES_TS_TO,
+		Types:         DEFAULT_FILES_TYPES,
+		Count:         DEFAULT_FILES_COUNT,
+		Page:          DEFAULT_FILES_PAGE,
+	}
+}
+
+func (api *Client) fileRequest(ctx context.Context, path string, values url.Values) (*fileResponseFull, error) {
+	response := &fileResponseFull{}
+	err := api.postMethod(ctx, path, values, response)
+	if err != nil {
+		return nil, err
+	}
+
+	return response, response.Err()
+}
+
+// GetFileInfo retrieves a file and related comments
+func (api *Client) GetFileInfo(fileID string, count, page int) (*File, []Comment, *Paging, error) {
+	return api.GetFileInfoContext(context.Background(), fileID, count, page)
+}
+
+// GetFileInfoContext retrieves a file and related comments with a custom context
+func (api *Client) GetFileInfoContext(ctx context.Context, fileID string, count, page int) (*File, []Comment, *Paging, error) {
+	values := url.Values{
+		"token": {api.token},
+		"file":  {fileID},
+		"count": {strconv.Itoa(count)},
+		"page":  {strconv.Itoa(page)},
+	}
+
+	response, err := api.fileRequest(ctx, "files.info", values)
+	if err != nil {
+		return nil, nil, nil, err
+	}
+	return &response.File, response.Comments, &response.Paging, nil
+}
+
+// GetFile retreives a given file from its private download URL
+func (api *Client) GetFile(downloadURL string, writer io.Writer) error {
+	return downloadFile(api.httpclient, api.token, downloadURL, writer, api)
+}
+
+// GetFiles retrieves all files according to the parameters given
+func (api *Client) GetFiles(params GetFilesParameters) ([]File, *Paging, error) {
+	return api.GetFilesContext(context.Background(), params)
+}
+
+// ListFiles retrieves all files according to the parameters given. Uses cursor based pagination.
+func (api *Client) ListFiles(params ListFilesParameters) ([]File, *ListFilesParameters, error) {
+	return api.ListFilesContext(context.Background(), params)
+}
+
+// ListFilesContext retrieves all files according to the parameters given with a custom context. Uses cursor based pagination.
+func (api *Client) ListFilesContext(ctx context.Context, params ListFilesParameters) ([]File, *ListFilesParameters, error) {
+	values := url.Values{
+		"token": {api.token},
+	}
+
+	if params.User != DEFAULT_FILES_USER {
+		values.Add("user", params.User)
+	}
+	if params.Channel != DEFAULT_FILES_CHANNEL {
+		values.Add("channel", params.Channel)
+	}
+	if params.Limit != DEFAULT_FILES_COUNT {
+		values.Add("limit", strconv.Itoa(params.Limit))
+	}
+	if params.Cursor != "" {
+		values.Add("cursor", params.Cursor)
+	}
+
+	response, err := api.fileRequest(ctx, "files.list", values)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	params.Cursor = response.Metadata.Cursor
+
+	return response.Files, &params, nil
+}
+
+// GetFilesContext retrieves all files according to the parameters given with a custom context
+func (api *Client) GetFilesContext(ctx context.Context, params GetFilesParameters) ([]File, *Paging, error) {
+	values := url.Values{
+		"token": {api.token},
+	}
+	if params.User != DEFAULT_FILES_USER {
+		values.Add("user", params.User)
+	}
+	if params.Channel != DEFAULT_FILES_CHANNEL {
+		values.Add("channel", params.Channel)
+	}
+	if params.TimestampFrom != DEFAULT_FILES_TS_FROM {
+		values.Add("ts_from", strconv.FormatInt(int64(params.TimestampFrom), 10))
+	}
+	if params.TimestampTo != DEFAULT_FILES_TS_TO {
+		values.Add("ts_to", strconv.FormatInt(int64(params.TimestampTo), 10))
+	}
+	if params.Types != DEFAULT_FILES_TYPES {
+		values.Add("types", params.Types)
+	}
+	if params.Count != DEFAULT_FILES_COUNT {
+		values.Add("count", strconv.Itoa(params.Count))
+	}
+	if params.Page != DEFAULT_FILES_PAGE {
+		values.Add("page", strconv.Itoa(params.Page))
+	}
+
+	response, err := api.fileRequest(ctx, "files.list", values)
+	if err != nil {
+		return nil, nil, err
+	}
+	return response.Files, &response.Paging, nil
+}
+
+// UploadFile uploads a file
+func (api *Client) UploadFile(params FileUploadParameters) (file *File, err error) {
+	return api.UploadFileContext(context.Background(), params)
+}
+
+// UploadFileContext uploads a file and setting a custom context
+func (api *Client) UploadFileContext(ctx context.Context, params FileUploadParameters) (file *File, err error) {
+	// Test if user token is valid. This helps because client.Do doesn't like this for some reason. XXX: More
+	// investigation needed, but for now this will do.
+	_, err = api.AuthTest()
+	if err != nil {
+		return nil, err
+	}
+	response := &fileResponseFull{}
+	values := url.Values{
+		"token": {api.token},
+	}
+	if params.Filetype != "" {
+		values.Add("filetype", params.Filetype)
+	}
+	if params.Filename != "" {
+		values.Add("filename", params.Filename)
+	}
+	if params.Title != "" {
+		values.Add("title", params.Title)
+	}
+	if params.InitialComment != "" {
+		values.Add("initial_comment", params.InitialComment)
+	}
+	if params.ThreadTimestamp != "" {
+		values.Add("thread_ts", params.ThreadTimestamp)
+	}
+	if len(params.Channels) != 0 {
+		values.Add("channels", strings.Join(params.Channels, ","))
+	}
+	if params.Content != "" {
+		values.Add("content", params.Content)
+		err = api.postMethod(ctx, "files.upload", values, response)
+	} else if params.File != "" {
+		err = postLocalWithMultipartResponse(ctx, api.httpclient, api.endpoint+"files.upload", params.File, "file", values, response, api)
+	} else if params.Reader != nil {
+		if params.Filename == "" {
+			return nil, fmt.Errorf("files.upload: FileUploadParameters.Filename is mandatory when using FileUploadParameters.Reader")
+		}
+		err = postWithMultipartResponse(ctx, api.httpclient, api.endpoint+"files.upload", params.Filename, "file", values, params.Reader, response, api)
+	}
+
+	if err != nil {
+		return nil, err
+	}
+
+	return &response.File, response.Err()
+}
+
+// DeleteFileComment deletes a file's comment
+func (api *Client) DeleteFileComment(commentID, fileID string) error {
+	return api.DeleteFileCommentContext(context.Background(), fileID, commentID)
+}
+
+// DeleteFileCommentContext deletes a file's comment with a custom context
+func (api *Client) DeleteFileCommentContext(ctx context.Context, fileID, commentID string) (err error) {
+	if fileID == "" || commentID == "" {
+		return ErrParametersMissing
+	}
+
+	values := url.Values{
+		"token": {api.token},
+		"file":  {fileID},
+		"id":    {commentID},
+	}
+	_, err = api.fileRequest(ctx, "files.comments.delete", values)
+	return err
+}
+
+// DeleteFile deletes a file
+func (api *Client) DeleteFile(fileID string) error {
+	return api.DeleteFileContext(context.Background(), fileID)
+}
+
+// DeleteFileContext deletes a file with a custom context
+func (api *Client) DeleteFileContext(ctx context.Context, fileID string) (err error) {
+	values := url.Values{
+		"token": {api.token},
+		"file":  {fileID},
+	}
+
+	_, err = api.fileRequest(ctx, "files.delete", values)
+	return err
+}
+
+// RevokeFilePublicURL disables public/external sharing for a file
+func (api *Client) RevokeFilePublicURL(fileID string) (*File, error) {
+	return api.RevokeFilePublicURLContext(context.Background(), fileID)
+}
+
+// RevokeFilePublicURLContext disables public/external sharing for a file with a custom context
+func (api *Client) RevokeFilePublicURLContext(ctx context.Context, fileID string) (*File, error) {
+	values := url.Values{
+		"token": {api.token},
+		"file":  {fileID},
+	}
+
+	response, err := api.fileRequest(ctx, "files.revokePublicURL", values)
+	if err != nil {
+		return nil, err
+	}
+	return &response.File, nil
+}
+
+// ShareFilePublicURL enabled public/external sharing for a file
+func (api *Client) ShareFilePublicURL(fileID string) (*File, []Comment, *Paging, error) {
+	return api.ShareFilePublicURLContext(context.Background(), fileID)
+}
+
+// ShareFilePublicURLContext enabled public/external sharing for a file with a custom context
+func (api *Client) ShareFilePublicURLContext(ctx context.Context, fileID string) (*File, []Comment, *Paging, error) {
+	values := url.Values{
+		"token": {api.token},
+		"file":  {fileID},
+	}
+
+	response, err := api.fileRequest(ctx, "files.sharedPublicURL", values)
+	if err != nil {
+		return nil, nil, nil, err
+	}
+	return &response.File, response.Comments, &response.Paging, nil
+}
diff --git a/vendor/github.com/slack-go/slack/go.mod b/vendor/github.com/slack-go/slack/go.mod
new file mode 100644
index 00000000..cbe11808
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/go.mod
@@ -0,0 +1,12 @@
+module github.com/slack-go/slack
+
+go 1.13
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/go-test/deep v1.0.4
+	github.com/gorilla/websocket v1.2.0
+	github.com/pkg/errors v0.8.0
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/stretchr/testify v1.2.2
+)
diff --git a/vendor/github.com/slack-go/slack/go.sum b/vendor/github.com/slack-go/slack/go.sum
new file mode 100644
index 00000000..7a0ae46e
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/go.sum
@@ -0,0 +1,12 @@
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/go-test/deep v1.0.4 h1:u2CU3YKy9I2pmu9pX0eq50wCgjfGIt539SqR7FbHiho=
+github.com/go-test/deep v1.0.4/go.mod h1:wGDj63lr65AM2AQyKZd/NYHGb0R+1RLqB8NKt3aSFNA=
+github.com/gorilla/websocket v1.2.0 h1:VJtLvh6VQym50czpZzx07z/kw9EgAxI3x1ZB8taTMQQ=
+github.com/gorilla/websocket v1.2.0/go.mod h1:E7qHFY5m1UJ88s3WnNqhKjPHQ0heANvMoAMk2YaljkQ=
+github.com/pkg/errors v0.8.0 h1:WdK/asTD0HN+q6hsWO3/vpuAkAr+tw6aNJNDFFf0+qw=
+github.com/pkg/errors v0.8.0/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINEl0=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/testify v1.2.2 h1:bSDNvY7ZPG5RlJ8otE/7V6gMiyenm9RtJ7IUVIAoJ1w=
+github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
diff --git a/vendor/github.com/slack-go/slack/groups.go b/vendor/github.com/slack-go/slack/groups.go
new file mode 100644
index 00000000..23374869
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/groups.go
@@ -0,0 +1,355 @@
+package slack
+
+import (
+	"context"
+	"net/url"
+	"strconv"
+)
+
+// Group contains all the information for a group
+type Group struct {
+	GroupConversation
+	IsGroup bool `json:"is_group"`
+}
+
+type groupResponseFull struct {
+	Group          Group   `json:"group"`
+	Groups         []Group `json:"groups"`
+	Purpose        string  `json:"purpose"`
+	Topic          string  `json:"topic"`
+	NotInGroup     bool    `json:"not_in_group"`
+	NoOp           bool    `json:"no_op"`
+	AlreadyClosed  bool    `json:"already_closed"`
+	AlreadyOpen    bool    `json:"already_open"`
+	AlreadyInGroup bool    `json:"already_in_group"`
+	Channel        Channel `json:"channel"`
+	History
+	SlackResponse
+}
+
+func (api *Client) groupRequest(ctx context.Context, path string, values url.Values) (*groupResponseFull, error) {
+	response := &groupResponseFull{}
+	err := api.postMethod(ctx, path, values, response)
+	if err != nil {
+		return nil, err
+	}
+
+	return response, response.Err()
+}
+
+// ArchiveGroup archives a private group
+func (api *Client) ArchiveGroup(group string) error {
+	return api.ArchiveGroupContext(context.Background(), group)
+}
+
+// ArchiveGroupContext archives a private group
+func (api *Client) ArchiveGroupContext(ctx context.Context, group string) error {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {group},
+	}
+
+	_, err := api.groupRequest(ctx, "groups.archive", values)
+	return err
+}
+
+// UnarchiveGroup unarchives a private group
+func (api *Client) UnarchiveGroup(group string) error {
+	return api.UnarchiveGroupContext(context.Background(), group)
+}
+
+// UnarchiveGroupContext unarchives a private group
+func (api *Client) UnarchiveGroupContext(ctx context.Context, group string) error {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {group},
+	}
+
+	_, err := api.groupRequest(ctx, "groups.unarchive", values)
+	return err
+}
+
+// CreateGroup creates a private group
+func (api *Client) CreateGroup(group string) (*Group, error) {
+	return api.CreateGroupContext(context.Background(), group)
+}
+
+// CreateGroupContext creates a private group
+func (api *Client) CreateGroupContext(ctx context.Context, group string) (*Group, error) {
+	values := url.Values{
+		"token": {api.token},
+		"name":  {group},
+	}
+
+	response, err := api.groupRequest(ctx, "groups.create", values)
+	if err != nil {
+		return nil, err
+	}
+	return &response.Group, nil
+}
+
+// CreateChildGroup creates a new private group archiving the old one
+// This method takes an existing private group and performs the following steps:
+//   1. Renames the existing group (from "example" to "example-archived").
+//   2. Archives the existing group.
+//   3. Creates a new group with the name of the existing group.
+//   4. Adds all members of the existing group to the new group.
+func (api *Client) CreateChildGroup(group string) (*Group, error) {
+	return api.CreateChildGroupContext(context.Background(), group)
+}
+
+// CreateChildGroupContext creates a new private group archiving the old one with a custom context
+// For more information see CreateChildGroup
+func (api *Client) CreateChildGroupContext(ctx context.Context, group string) (*Group, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {group},
+	}
+
+	response, err := api.groupRequest(ctx, "groups.createChild", values)
+	if err != nil {
+		return nil, err
+	}
+	return &response.Group, nil
+}
+
+// GetGroupHistory fetches all the history for a private group
+func (api *Client) GetGroupHistory(group string, params HistoryParameters) (*History, error) {
+	return api.GetGroupHistoryContext(context.Background(), group, params)
+}
+
+// GetGroupHistoryContext fetches all the history for a private group with a custom context
+func (api *Client) GetGroupHistoryContext(ctx context.Context, group string, params HistoryParameters) (*History, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {group},
+	}
+	if params.Latest != DEFAULT_HISTORY_LATEST {
+		values.Add("latest", params.Latest)
+	}
+	if params.Oldest != DEFAULT_HISTORY_OLDEST {
+		values.Add("oldest", params.Oldest)
+	}
+	if params.Count != DEFAULT_HISTORY_COUNT {
+		values.Add("count", strconv.Itoa(params.Count))
+	}
+	if params.Inclusive != DEFAULT_HISTORY_INCLUSIVE {
+		if params.Inclusive {
+			values.Add("inclusive", "1")
+		} else {
+			values.Add("inclusive", "0")
+		}
+	}
+	if params.Unreads != DEFAULT_HISTORY_UNREADS {
+		if params.Unreads {
+			values.Add("unreads", "1")
+		} else {
+			values.Add("unreads", "0")
+		}
+	}
+
+	response, err := api.groupRequest(ctx, "groups.history", values)
+	if err != nil {
+		return nil, err
+	}
+	return &response.History, nil
+}
+
+// InviteUserToGroup invites a specific user to a private group
+func (api *Client) InviteUserToGroup(group, user string) (*Group, bool, error) {
+	return api.InviteUserToGroupContext(context.Background(), group, user)
+}
+
+// InviteUserToGroupContext invites a specific user to a private group with a custom context
+func (api *Client) InviteUserToGroupContext(ctx context.Context, group, user string) (*Group, bool, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {group},
+		"user":    {user},
+	}
+
+	response, err := api.groupRequest(ctx, "groups.invite", values)
+	if err != nil {
+		return nil, false, err
+	}
+	return &response.Group, response.AlreadyInGroup, nil
+}
+
+// LeaveGroup makes authenticated user leave the group
+func (api *Client) LeaveGroup(group string) error {
+	return api.LeaveGroupContext(context.Background(), group)
+}
+
+// LeaveGroupContext makes authenticated user leave the group with a custom context
+func (api *Client) LeaveGroupContext(ctx context.Context, group string) (err error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {group},
+	}
+
+	_, err = api.groupRequest(ctx, "groups.leave", values)
+	return err
+}
+
+// KickUserFromGroup kicks a user from a group
+func (api *Client) KickUserFromGroup(group, user string) error {
+	return api.KickUserFromGroupContext(context.Background(), group, user)
+}
+
+// KickUserFromGroupContext kicks a user from a group with a custom context
+func (api *Client) KickUserFromGroupContext(ctx context.Context, group, user string) (err error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {group},
+		"user":    {user},
+	}
+
+	_, err = api.groupRequest(ctx, "groups.kick", values)
+	return err
+}
+
+// GetGroups retrieves all groups
+func (api *Client) GetGroups(excludeArchived bool) ([]Group, error) {
+	return api.GetGroupsContext(context.Background(), excludeArchived)
+}
+
+// GetGroupsContext retrieves all groups with a custom context
+func (api *Client) GetGroupsContext(ctx context.Context, excludeArchived bool) ([]Group, error) {
+	values := url.Values{
+		"token": {api.token},
+	}
+	if excludeArchived {
+		values.Add("exclude_archived", "1")
+	}
+
+	response, err := api.groupRequest(ctx, "groups.list", values)
+	if err != nil {
+		return nil, err
+	}
+	return response.Groups, nil
+}
+
+// GetGroupInfo retrieves the given group
+func (api *Client) GetGroupInfo(group string) (*Group, error) {
+	return api.GetGroupInfoContext(context.Background(), group)
+}
+
+// GetGroupInfoContext retrieves the given group with a custom context
+func (api *Client) GetGroupInfoContext(ctx context.Context, group string) (*Group, error) {
+	values := url.Values{
+		"token":          {api.token},
+		"channel":        {group},
+		"include_locale": {strconv.FormatBool(true)},
+	}
+
+	response, err := api.groupRequest(ctx, "groups.info", values)
+	if err != nil {
+		return nil, err
+	}
+	return &response.Group, nil
+}
+
+// SetGroupReadMark sets the read mark on a private group
+// Clients should try to avoid making this call too often. When needing to mark a read position, a client should set a
+// timer before making the call. In this way, any further updates needed during the timeout will not generate extra
+// calls (just one per channel). This is useful for when reading scroll-back history, or following a busy live
+// channel. A timeout of 5 seconds is a good starting point. Be sure to flush these calls on shutdown/logout.
+func (api *Client) SetGroupReadMark(group, ts string) error {
+	return api.SetGroupReadMarkContext(context.Background(), group, ts)
+}
+
+// SetGroupReadMarkContext sets the read mark on a private group with a custom context
+// For more details see SetGroupReadMark
+func (api *Client) SetGroupReadMarkContext(ctx context.Context, group, ts string) (err error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {group},
+		"ts":      {ts},
+	}
+
+	_, err = api.groupRequest(ctx, "groups.mark", values)
+	return err
+}
+
+// OpenGroup opens a private group
+func (api *Client) OpenGroup(group string) (bool, bool, error) {
+	return api.OpenGroupContext(context.Background(), group)
+}
+
+// OpenGroupContext opens a private group with a custom context
+func (api *Client) OpenGroupContext(ctx context.Context, group string) (bool, bool, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {group},
+	}
+
+	response, err := api.groupRequest(ctx, "groups.open", values)
+	if err != nil {
+		return false, false, err
+	}
+	return response.NoOp, response.AlreadyOpen, nil
+}
+
+// RenameGroup renames a group
+// XXX: They return a channel, not a group. What is this crap? :(
+// Inconsistent api it seems.
+func (api *Client) RenameGroup(group, name string) (*Channel, error) {
+	return api.RenameGroupContext(context.Background(), group, name)
+}
+
+// RenameGroupContext renames a group with a custom context
+func (api *Client) RenameGroupContext(ctx context.Context, group, name string) (*Channel, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {group},
+		"name":    {name},
+	}
+
+	// XXX: the created entry in this call returns a string instead of a number
+	// so I may have to do some workaround to solve it.
+	response, err := api.groupRequest(ctx, "groups.rename", values)
+	if err != nil {
+		return nil, err
+	}
+	return &response.Channel, nil
+}
+
+// SetGroupPurpose sets the group purpose
+func (api *Client) SetGroupPurpose(group, purpose string) (string, error) {
+	return api.SetGroupPurposeContext(context.Background(), group, purpose)
+}
+
+// SetGroupPurposeContext sets the group purpose with a custom context
+func (api *Client) SetGroupPurposeContext(ctx context.Context, group, purpose string) (string, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {group},
+		"purpose": {purpose},
+	}
+
+	response, err := api.groupRequest(ctx, "groups.setPurpose", values)
+	if err != nil {
+		return "", err
+	}
+	return response.Purpose, nil
+}
+
+// SetGroupTopic sets the group topic
+func (api *Client) SetGroupTopic(group, topic string) (string, error) {
+	return api.SetGroupTopicContext(context.Background(), group, topic)
+}
+
+// SetGroupTopicContext sets the group topic with a custom context
+func (api *Client) SetGroupTopicContext(ctx context.Context, group, topic string) (string, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {group},
+		"topic":   {topic},
+	}
+
+	response, err := api.groupRequest(ctx, "groups.setTopic", values)
+	if err != nil {
+		return "", err
+	}
+	return response.Topic, nil
+}
diff --git a/vendor/github.com/slack-go/slack/history.go b/vendor/github.com/slack-go/slack/history.go
new file mode 100644
index 00000000..87b2e1ed
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/history.go
@@ -0,0 +1,36 @@
+package slack
+
+const (
+	DEFAULT_HISTORY_LATEST    = ""
+	DEFAULT_HISTORY_OLDEST    = "0"
+	DEFAULT_HISTORY_COUNT     = 100
+	DEFAULT_HISTORY_INCLUSIVE = false
+	DEFAULT_HISTORY_UNREADS   = false
+)
+
+// HistoryParameters contains all the necessary information to help in the retrieval of history for Channels/Groups/DMs
+type HistoryParameters struct {
+	Latest    string
+	Oldest    string
+	Count     int
+	Inclusive bool
+	Unreads   bool
+}
+
+// History contains message history information needed to navigate a Channel / Group / DM history
+type History struct {
+	Latest   string    `json:"latest"`
+	Messages []Message `json:"messages"`
+	HasMore  bool      `json:"has_more"`
+}
+
+// NewHistoryParameters provides an instance of HistoryParameters with all the sane default values set
+func NewHistoryParameters() HistoryParameters {
+	return HistoryParameters{
+		Latest:    DEFAULT_HISTORY_LATEST,
+		Oldest:    DEFAULT_HISTORY_OLDEST,
+		Count:     DEFAULT_HISTORY_COUNT,
+		Inclusive: DEFAULT_HISTORY_INCLUSIVE,
+		Unreads:   DEFAULT_HISTORY_UNREADS,
+	}
+}
diff --git a/vendor/github.com/slack-go/slack/im.go b/vendor/github.com/slack-go/slack/im.go
new file mode 100644
index 00000000..ee784fef
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/im.go
@@ -0,0 +1,154 @@
+package slack
+
+import (
+	"context"
+	"net/url"
+	"strconv"
+)
+
+type imChannel struct {
+	ID string `json:"id"`
+}
+
+type imResponseFull struct {
+	NoOp          bool      `json:"no_op"`
+	AlreadyClosed bool      `json:"already_closed"`
+	AlreadyOpen   bool      `json:"already_open"`
+	Channel       imChannel `json:"channel"`
+	IMs           []IM      `json:"ims"`
+	History
+	SlackResponse
+}
+
+// IM contains information related to the Direct Message channel
+type IM struct {
+	Conversation
+	IsUserDeleted bool `json:"is_user_deleted"`
+}
+
+func (api *Client) imRequest(ctx context.Context, path string, values url.Values) (*imResponseFull, error) {
+	response := &imResponseFull{}
+	err := api.postMethod(ctx, path, values, response)
+	if err != nil {
+		return nil, err
+	}
+
+	return response, response.Err()
+}
+
+// CloseIMChannel closes the direct message channel
+func (api *Client) CloseIMChannel(channel string) (bool, bool, error) {
+	return api.CloseIMChannelContext(context.Background(), channel)
+}
+
+// CloseIMChannelContext closes the direct message channel with a custom context
+func (api *Client) CloseIMChannelContext(ctx context.Context, channel string) (bool, bool, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channel},
+	}
+
+	response, err := api.imRequest(ctx, "im.close", values)
+	if err != nil {
+		return false, false, err
+	}
+	return response.NoOp, response.AlreadyClosed, nil
+}
+
+// OpenIMChannel opens a direct message channel to the user provided as argument
+// Returns some status and the channel ID
+func (api *Client) OpenIMChannel(user string) (bool, bool, string, error) {
+	return api.OpenIMChannelContext(context.Background(), user)
+}
+
+// OpenIMChannelContext opens a direct message channel to the user provided as argument with a custom context
+// Returns some status and the channel ID
+func (api *Client) OpenIMChannelContext(ctx context.Context, user string) (bool, bool, string, error) {
+	values := url.Values{
+		"token": {api.token},
+		"user":  {user},
+	}
+
+	response, err := api.imRequest(ctx, "im.open", values)
+	if err != nil {
+		return false, false, "", err
+	}
+	return response.NoOp, response.AlreadyOpen, response.Channel.ID, nil
+}
+
+// MarkIMChannel sets the read mark of a direct message channel to a specific point
+func (api *Client) MarkIMChannel(channel, ts string) (err error) {
+	return api.MarkIMChannelContext(context.Background(), channel, ts)
+}
+
+// MarkIMChannelContext sets the read mark of a direct message channel to a specific point with a custom context
+func (api *Client) MarkIMChannelContext(ctx context.Context, channel, ts string) error {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channel},
+		"ts":      {ts},
+	}
+
+	_, err := api.imRequest(ctx, "im.mark", values)
+	return err
+}
+
+// GetIMHistory retrieves the direct message channel history
+func (api *Client) GetIMHistory(channel string, params HistoryParameters) (*History, error) {
+	return api.GetIMHistoryContext(context.Background(), channel, params)
+}
+
+// GetIMHistoryContext retrieves the direct message channel history with a custom context
+func (api *Client) GetIMHistoryContext(ctx context.Context, channel string, params HistoryParameters) (*History, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"channel": {channel},
+	}
+	if params.Latest != DEFAULT_HISTORY_LATEST {
+		values.Add("latest", params.Latest)
+	}
+	if params.Oldest != DEFAULT_HISTORY_OLDEST {
+		values.Add("oldest", params.Oldest)
+	}
+	if params.Count != DEFAULT_HISTORY_COUNT {
+		values.Add("count", strconv.Itoa(params.Count))
+	}
+	if params.Inclusive != DEFAULT_HISTORY_INCLUSIVE {
+		if params.Inclusive {
+			values.Add("inclusive", "1")
+		} else {
+			values.Add("inclusive", "0")
+		}
+	}
+	if params.Unreads != DEFAULT_HISTORY_UNREADS {
+		if params.Unreads {
+			values.Add("unreads", "1")
+		} else {
+			values.Add("unreads", "0")
+		}
+	}
+
+	response, err := api.imRequest(ctx, "im.history", values)
+	if err != nil {
+		return nil, err
+	}
+	return &response.History, nil
+}
+
+// GetIMChannels returns the list of direct message channels
+func (api *Client) GetIMChannels() ([]IM, error) {
+	return api.GetIMChannelsContext(context.Background())
+}
+
+// GetIMChannelsContext returns the list of direct message channels with a custom context
+func (api *Client) GetIMChannelsContext(ctx context.Context) ([]IM, error) {
+	values := url.Values{
+		"token": {api.token},
+	}
+
+	response, err := api.imRequest(ctx, "im.list", values)
+	if err != nil {
+		return nil, err
+	}
+	return response.IMs, nil
+}
diff --git a/vendor/github.com/slack-go/slack/info.go b/vendor/github.com/slack-go/slack/info.go
new file mode 100644
index 00000000..31f459f1
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/info.go
@@ -0,0 +1,195 @@
+package slack
+
+import (
+	"bytes"
+	"fmt"
+	"strconv"
+	"time"
+)
+
+// UserPrefs needs to be implemented
+type UserPrefs struct {
+	// "highlight_words":"",
+	// "user_colors":"",
+	// "color_names_in_list":true,
+	// "growls_enabled":true,
+	// "tz":"Europe\/London",
+	// "push_dm_alert":true,
+	// "push_mention_alert":true,
+	// "push_everything":true,
+	// "push_idle_wait":2,
+	// "push_sound":"b2.mp3",
+	// "push_loud_channels":"",
+	// "push_mention_channels":"",
+	// "push_loud_channels_set":"",
+	// "email_alerts":"instant",
+	// "email_alerts_sleep_until":0,
+	// "email_misc":false,
+	// "email_weekly":true,
+	// "welcome_message_hidden":false,
+	// "all_channels_loud":true,
+	// "loud_channels":"",
+	// "never_channels":"",
+	// "loud_channels_set":"",
+	// "show_member_presence":true,
+	// "search_sort":"timestamp",
+	// "expand_inline_imgs":true,
+	// "expand_internal_inline_imgs":true,
+	// "expand_snippets":false,
+	// "posts_formatting_guide":true,
+	// "seen_welcome_2":true,
+	// "seen_ssb_prompt":false,
+	// "search_only_my_channels":false,
+	// "emoji_mode":"default",
+	// "has_invited":true,
+	// "has_uploaded":false,
+	// "has_created_channel":true,
+	// "search_exclude_channels":"",
+	// "messages_theme":"default",
+	// "webapp_spellcheck":true,
+	// "no_joined_overlays":false,
+	// "no_created_overlays":true,
+	// "dropbox_enabled":false,
+	// "seen_user_menu_tip_card":true,
+	// "seen_team_menu_tip_card":true,
+	// "seen_channel_menu_tip_card":true,
+	// "seen_message_input_tip_card":true,
+	// "seen_channels_tip_card":true,
+	// "seen_domain_invite_reminder":false,
+	// "seen_member_invite_reminder":false,
+	// "seen_flexpane_tip_card":true,
+	// "seen_search_input_tip_card":true,
+	// "mute_sounds":false,
+	// "arrow_history":false,
+	// "tab_ui_return_selects":true,
+	// "obey_inline_img_limit":true,
+	// "new_msg_snd":"knock_brush.mp3",
+	// "collapsible":false,
+	// "collapsible_by_click":true,
+	// "require_at":false,
+	// "mac_ssb_bounce":"",
+	// "mac_ssb_bullet":true,
+	// "win_ssb_bullet":true,
+	// "expand_non_media_attachments":true,
+	// "show_typing":true,
+	// "pagekeys_handled":true,
+	// "last_snippet_type":"",
+	// "display_real_names_override":0,
+	// "time24":false,
+	// "enter_is_special_in_tbt":false,
+	// "graphic_emoticons":false,
+	// "convert_emoticons":true,
+	// "autoplay_chat_sounds":true,
+	// "ss_emojis":true,
+	// "sidebar_behavior":"",
+	// "mark_msgs_read_immediately":true,
+	// "start_scroll_at_oldest":true,
+	// "snippet_editor_wrap_long_lines":false,
+	// "ls_disabled":false,
+	// "sidebar_theme":"default",
+	// "sidebar_theme_custom_values":"",
+	// "f_key_search":false,
+	// "k_key_omnibox":true,
+	// "speak_growls":false,
+	// "mac_speak_voice":"com.apple.speech.synthesis.voice.Alex",
+	// "mac_speak_speed":250,
+	// "comma_key_prefs":false,
+	// "at_channel_suppressed_channels":"",
+	// "push_at_channel_suppressed_channels":"",
+	// "prompted_for_email_disabling":false,
+	// "full_text_extracts":false,
+	// "no_text_in_notifications":false,
+	// "muted_channels":"",
+	// "no_macssb1_banner":false,
+	// "privacy_policy_seen":true,
+	// "search_exclude_bots":false,
+	// "fuzzy_matching":false
+}
+
+// UserDetails contains user details coming in the initial response from StartRTM
+type UserDetails struct {
+	ID             string    `json:"id"`
+	Name           string    `json:"name"`
+	Created        JSONTime  `json:"created"`
+	ManualPresence string    `json:"manual_presence"`
+	Prefs          UserPrefs `json:"prefs"`
+}
+
+// JSONTime exists so that we can have a String method converting the date
+type JSONTime int64
+
+// String converts the unix timestamp into a string
+func (t JSONTime) String() string {
+	tm := t.Time()
+	return fmt.Sprintf("\"%s\"", tm.Format("Mon Jan _2"))
+}
+
+// Time returns a `time.Time` representation of this value.
+func (t JSONTime) Time() time.Time {
+	return time.Unix(int64(t), 0)
+}
+
+// UnmarshalJSON will unmarshal both string and int JSON values
+func (t *JSONTime) UnmarshalJSON(buf []byte) error {
+	s := bytes.Trim(buf, `"`)
+
+	v, err := strconv.Atoi(string(s))
+	if err != nil {
+		return err
+	}
+
+	*t = JSONTime(int64(v))
+	return nil
+}
+
+// Team contains details about a team
+type Team struct {
+	ID     string `json:"id"`
+	Name   string `json:"name"`
+	Domain string `json:"domain"`
+}
+
+// Icons XXX: needs further investigation
+type Icons struct {
+	Image36 string `json:"image_36,omitempty"`
+	Image48 string `json:"image_48,omitempty"`
+	Image72 string `json:"image_72,omitempty"`
+}
+
+// Info contains various details about the authenticated user and team.
+// It is returned by StartRTM or included in the "ConnectedEvent" RTM event.
+type Info struct {
+	URL  string       `json:"url,omitempty"`
+	User *UserDetails `json:"self,omitempty"`
+	Team *Team        `json:"team,omitempty"`
+}
+
+type infoResponseFull struct {
+	Info
+	SlackResponse
+}
+
+// GetBotByID is deprecated and returns nil
+func (info Info) GetBotByID(botID string) *Bot {
+	return nil
+}
+
+// GetUserByID is deprecated and returns nil
+func (info Info) GetUserByID(userID string) *User {
+	return nil
+}
+
+// GetChannelByID is deprecated and returns nil
+func (info Info) GetChannelByID(channelID string) *Channel {
+	return nil
+}
+
+// GetGroupByID is deprecated and returns nil
+func (info Info) GetGroupByID(groupID string) *Group {
+	return nil
+}
+
+// GetIMByID is deprecated and returns nil
+func (info Info) GetIMByID(imID string) *IM {
+	return nil
+}
diff --git a/vendor/github.com/slack-go/slack/interactions.go b/vendor/github.com/slack-go/slack/interactions.go
new file mode 100644
index 00000000..26a8b6db
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/interactions.go
@@ -0,0 +1,142 @@
+package slack
+
+import (
+	"bytes"
+	"encoding/json"
+)
+
+// InteractionType type of interactions
+type InteractionType string
+
+// ActionType type represents the type of action (attachment, block, etc.)
+type actionType string
+
+// action is an interface that should be implemented by all callback action types
+type action interface {
+	actionType() actionType
+}
+
+// Types of interactions that can be received.
+const (
+	InteractionTypeDialogCancellation = InteractionType("dialog_cancellation")
+	InteractionTypeDialogSubmission   = InteractionType("dialog_submission")
+	InteractionTypeDialogSuggestion   = InteractionType("dialog_suggestion")
+	InteractionTypeInteractionMessage = InteractionType("interactive_message")
+	InteractionTypeMessageAction      = InteractionType("message_action")
+	InteractionTypeBlockActions       = InteractionType("block_actions")
+)
+
+// InteractionCallback is sent from slack when a user interactions with a button or dialog.
+type InteractionCallback struct {
+	Type            InteractionType `json:"type"`
+	Token           string          `json:"token"`
+	CallbackID      string          `json:"callback_id"`
+	ResponseURL     string          `json:"response_url"`
+	TriggerID       string          `json:"trigger_id"`
+	ActionTs        string          `json:"action_ts"`
+	Team            Team            `json:"team"`
+	Channel         Channel         `json:"channel"`
+	User            User            `json:"user"`
+	OriginalMessage Message         `json:"original_message"`
+	Message         Message         `json:"message"`
+	Name            string          `json:"name"`
+	Value           string          `json:"value"`
+	MessageTs       string          `json:"message_ts"`
+	AttachmentID    string          `json:"attachment_id"`
+	ActionCallback  ActionCallbacks `json:"actions"`
+	APIAppID        string          `json:"api_app_id"`
+	DialogSubmissionCallback
+}
+
+// ActionCallback is a convenience struct defined to allow dynamic unmarshalling of
+// the "actions" value in Slack's JSON response, which varies depending on block type
+type ActionCallbacks struct {
+	AttachmentActions []*AttachmentAction
+	BlockActions      []*BlockAction
+}
+
+// MarshalJSON implements the Marshaller interface in order to combine both
+// action callback types back into a single array, like how the api responds.
+// This makes Marshaling and Unmarshaling an InteractionCallback symmetrical
+func (a ActionCallbacks) MarshalJSON() ([]byte, error) {
+	count := 0
+	length := len(a.AttachmentActions) + len(a.BlockActions)
+	buffer := bytes.NewBufferString("[")
+
+	f := func(obj interface{}) error {
+		js, err := json.Marshal(obj)
+		if err != nil {
+			return err
+		}
+		_, err = buffer.Write(js)
+		if err != nil {
+			return err
+		}
+
+		count++
+		if count < length {
+			_, err = buffer.WriteString(",")
+			return err
+		}
+		return nil
+	}
+
+	for _, act := range a.AttachmentActions {
+		err := f(act)
+		if err != nil {
+			return nil, err
+		}
+	}
+	for _, blk := range a.BlockActions {
+		err := f(blk)
+		if err != nil {
+			return nil, err
+		}
+	}
+	buffer.WriteString("]")
+	return buffer.Bytes(), nil
+}
+
+// UnmarshalJSON implements the Marshaller interface in order to delegate
+// marshalling and allow for proper type assertion when decoding the response
+func (a *ActionCallbacks) UnmarshalJSON(data []byte) error {
+	var raw []json.RawMessage
+	err := json.Unmarshal(data, &raw)
+	if err != nil {
+		return err
+	}
+
+	for _, r := range raw {
+		var obj map[string]interface{}
+		err := json.Unmarshal(r, &obj)
+		if err != nil {
+			return err
+		}
+
+		if _, ok := obj["block_id"].(string); ok {
+			action, err := unmarshalAction(r, &BlockAction{})
+			if err != nil {
+				return err
+			}
+
+			a.BlockActions = append(a.BlockActions, action.(*BlockAction))
+			return nil
+		}
+
+		action, err := unmarshalAction(r, &AttachmentAction{})
+		if err != nil {
+			return err
+		}
+		a.AttachmentActions = append(a.AttachmentActions, action.(*AttachmentAction))
+	}
+
+	return nil
+}
+
+func unmarshalAction(r json.RawMessage, callbackAction action) (action, error) {
+	err := json.Unmarshal(r, callbackAction)
+	if err != nil {
+		return nil, err
+	}
+	return callbackAction, nil
+}
diff --git a/vendor/github.com/slack-go/slack/internal/errorsx/errorsx.go b/vendor/github.com/slack-go/slack/internal/errorsx/errorsx.go
new file mode 100644
index 00000000..cb850577
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/internal/errorsx/errorsx.go
@@ -0,0 +1,8 @@
+package errorsx
+
+// String representing an error, useful for declaring string constants as errors.
+type String string
+
+func (t String) Error() string {
+	return string(t)
+}
diff --git a/vendor/github.com/slack-go/slack/internal/timex/timex.go b/vendor/github.com/slack-go/slack/internal/timex/timex.go
new file mode 100644
index 00000000..40063f73
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/internal/timex/timex.go
@@ -0,0 +1,18 @@
+package timex
+
+import "time"
+
+// Max returns the maximum duration
+func Max(values ...time.Duration) time.Duration {
+	var (
+		max time.Duration
+	)
+
+	for _, v := range values {
+		if v > max {
+			max = v
+		}
+	}
+
+	return max
+}
diff --git a/vendor/github.com/slack-go/slack/item.go b/vendor/github.com/slack-go/slack/item.go
new file mode 100644
index 00000000..89af4eb1
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/item.go
@@ -0,0 +1,75 @@
+package slack
+
+const (
+	TYPE_MESSAGE      = "message"
+	TYPE_FILE         = "file"
+	TYPE_FILE_COMMENT = "file_comment"
+	TYPE_CHANNEL      = "channel"
+	TYPE_IM           = "im"
+	TYPE_GROUP        = "group"
+)
+
+// Item is any type of slack message - message, file, or file comment.
+type Item struct {
+	Type      string   `json:"type"`
+	Channel   string   `json:"channel,omitempty"`
+	Message   *Message `json:"message,omitempty"`
+	File      *File    `json:"file,omitempty"`
+	Comment   *Comment `json:"comment,omitempty"`
+	Timestamp string   `json:"ts,omitempty"`
+}
+
+// NewMessageItem turns a message on a channel into a typed message struct.
+func NewMessageItem(ch string, m *Message) Item {
+	return Item{Type: TYPE_MESSAGE, Channel: ch, Message: m}
+}
+
+// NewFileItem turns a file into a typed file struct.
+func NewFileItem(f *File) Item {
+	return Item{Type: TYPE_FILE, File: f}
+}
+
+// NewFileCommentItem turns a file and comment into a typed file_comment struct.
+func NewFileCommentItem(f *File, c *Comment) Item {
+	return Item{Type: TYPE_FILE_COMMENT, File: f, Comment: c}
+}
+
+// NewChannelItem turns a channel id into a typed channel struct.
+func NewChannelItem(ch string) Item {
+	return Item{Type: TYPE_CHANNEL, Channel: ch}
+}
+
+// NewIMItem turns a channel id into a typed im struct.
+func NewIMItem(ch string) Item {
+	return Item{Type: TYPE_IM, Channel: ch}
+}
+
+// NewGroupItem turns a channel id into a typed group struct.
+func NewGroupItem(ch string) Item {
+	return Item{Type: TYPE_GROUP, Channel: ch}
+}
+
+// ItemRef is a reference to a message of any type. One of FileID,
+// CommentId, or the combination of ChannelId and Timestamp must be
+// specified.
+type ItemRef struct {
+	Channel   string `json:"channel"`
+	Timestamp string `json:"timestamp"`
+	File      string `json:"file"`
+	Comment   string `json:"file_comment"`
+}
+
+// NewRefToMessage initializes a reference to to a message.
+func NewRefToMessage(channel, timestamp string) ItemRef {
+	return ItemRef{Channel: channel, Timestamp: timestamp}
+}
+
+// NewRefToFile initializes a reference to a file.
+func NewRefToFile(file string) ItemRef {
+	return ItemRef{File: file}
+}
+
+// NewRefToComment initializes a reference to a file comment.
+func NewRefToComment(comment string) ItemRef {
+	return ItemRef{Comment: comment}
+}
diff --git a/vendor/github.com/slack-go/slack/logger.go b/vendor/github.com/slack-go/slack/logger.go
new file mode 100644
index 00000000..6a3533a9
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/logger.go
@@ -0,0 +1,60 @@
+package slack
+
+import (
+	"fmt"
+)
+
+// logger is a logger interface compatible with both stdlib and some
+// 3rd party loggers.
+type logger interface {
+	Output(int, string) error
+}
+
+// ilogger represents the internal logging api we use.
+type ilogger interface {
+	logger
+	Print(...interface{})
+	Printf(string, ...interface{})
+	Println(...interface{})
+}
+
+type debug interface {
+	Debug() bool
+
+	// Debugf print a formatted debug line.
+	Debugf(format string, v ...interface{})
+	// Debugln print a debug line.
+	Debugln(v ...interface{})
+}
+
+// internalLog implements the additional methods used by our internal logging.
+type internalLog struct {
+	logger
+}
+
+// Println replicates the behaviour of the standard logger.
+func (t internalLog) Println(v ...interface{}) {
+	t.Output(2, fmt.Sprintln(v...))
+}
+
+// Printf replicates the behaviour of the standard logger.
+func (t internalLog) Printf(format string, v ...interface{}) {
+	t.Output(2, fmt.Sprintf(format, v...))
+}
+
+// Print replicates the behaviour of the standard logger.
+func (t internalLog) Print(v ...interface{}) {
+	t.Output(2, fmt.Sprint(v...))
+}
+
+type discard struct{}
+
+func (t discard) Debug() bool {
+	return false
+}
+
+// Debugf print a formatted debug line.
+func (t discard) Debugf(format string, v ...interface{}) {}
+
+// Debugln print a debug line.
+func (t discard) Debugln(v ...interface{}) {}
diff --git a/vendor/github.com/slack-go/slack/messageID.go b/vendor/github.com/slack-go/slack/messageID.go
new file mode 100644
index 00000000..a17472b4
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/messageID.go
@@ -0,0 +1,30 @@
+package slack
+
+import "sync"
+
+// IDGenerator provides an interface for generating integer ID values.
+type IDGenerator interface {
+	Next() int
+}
+
+// NewSafeID returns a new instance of an IDGenerator which is safe for
+// concurrent use by multiple goroutines.
+func NewSafeID(startID int) IDGenerator {
+	return &safeID{
+		nextID: startID,
+		mutex:  &sync.Mutex{},
+	}
+}
+
+type safeID struct {
+	nextID int
+	mutex  *sync.Mutex
+}
+
+func (s *safeID) Next() int {
+	s.mutex.Lock()
+	defer s.mutex.Unlock()
+	id := s.nextID
+	s.nextID++
+	return id
+}
diff --git a/vendor/github.com/slack-go/slack/messages.go b/vendor/github.com/slack-go/slack/messages.go
new file mode 100644
index 00000000..f2f5b145
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/messages.go
@@ -0,0 +1,199 @@
+package slack
+
+// OutgoingMessage is used for the realtime API, and seems incomplete.
+type OutgoingMessage struct {
+	ID int `json:"id"`
+	// channel ID
+	Channel         string   `json:"channel,omitempty"`
+	Text            string   `json:"text,omitempty"`
+	Type            string   `json:"type,omitempty"`
+	ThreadTimestamp string   `json:"thread_ts,omitempty"`
+	ThreadBroadcast bool     `json:"reply_broadcast,omitempty"`
+	IDs             []string `json:"ids,omitempty"`
+}
+
+// Message is an auxiliary type to allow us to have a message containing sub messages
+type Message struct {
+	Msg
+	SubMessage      *Msg `json:"message,omitempty"`
+	PreviousMessage *Msg `json:"previous_message,omitempty"`
+}
+
+// Msg contains information about a slack message
+type Msg struct {
+	// Basic Message
+	ClientMsgID     string       `json:"client_msg_id"`
+	Type            string       `json:"type,omitempty"`
+	Channel         string       `json:"channel,omitempty"`
+	User            string       `json:"user,omitempty"`
+	Text            string       `json:"text,omitempty"`
+	Timestamp       string       `json:"ts,omitempty"`
+	ThreadTimestamp string       `json:"thread_ts,omitempty"`
+	IsStarred       bool         `json:"is_starred,omitempty"`
+	PinnedTo        []string     `json:"pinned_to,omitempty"`
+	Attachments     []Attachment `json:"attachments,omitempty"`
+	Edited          *Edited      `json:"edited,omitempty"`
+	LastRead        string       `json:"last_read,omitempty"`
+	Subscribed      bool         `json:"subscribed,omitempty"`
+	UnreadCount     int          `json:"unread_count,omitempty"`
+
+	// Message Subtypes
+	SubType string `json:"subtype,omitempty"`
+
+	// Hidden Subtypes
+	Hidden           bool   `json:"hidden,omitempty"`     // message_changed, message_deleted, unpinned_item
+	DeletedTimestamp string `json:"deleted_ts,omitempty"` // message_deleted
+	EventTimestamp   string `json:"event_ts,omitempty"`
+
+	// bot_message (https://api.slack.com/events/message/bot_message)
+	BotID    string `json:"bot_id,omitempty"`
+	Username string `json:"username,omitempty"`
+	Icons    *Icon  `json:"icons,omitempty"`
+
+	// channel_join, group_join
+	Inviter string `json:"inviter,omitempty"`
+
+	// channel_topic, group_topic
+	Topic string `json:"topic,omitempty"`
+
+	// channel_purpose, group_purpose
+	Purpose string `json:"purpose,omitempty"`
+
+	// channel_name, group_name
+	Name    string `json:"name,omitempty"`
+	OldName string `json:"old_name,omitempty"`
+
+	// channel_archive, group_archive
+	Members []string `json:"members,omitempty"`
+
+	// channels.replies, groups.replies, im.replies, mpim.replies
+	ReplyCount   int     `json:"reply_count,omitempty"`
+	Replies      []Reply `json:"replies,omitempty"`
+	ParentUserId string  `json:"parent_user_id,omitempty"`
+
+	// file_share, file_comment, file_mention
+	Files []File `json:"files,omitempty"`
+
+	// file_share
+	Upload bool `json:"upload,omitempty"`
+
+	// file_comment
+	Comment *Comment `json:"comment,omitempty"`
+
+	// pinned_item
+	ItemType string `json:"item_type,omitempty"`
+
+	// https://api.slack.com/rtm
+	ReplyTo int    `json:"reply_to,omitempty"`
+	Team    string `json:"team,omitempty"`
+
+	// reactions
+	Reactions []ItemReaction `json:"reactions,omitempty"`
+
+	// slash commands and interactive messages
+	ResponseType    string `json:"response_type,omitempty"`
+	ReplaceOriginal bool   `json:"replace_original"`
+	DeleteOriginal  bool   `json:"delete_original"`
+
+	// Block type Message
+	Blocks Blocks `json:"blocks,omitempty"`
+}
+
+const (
+	// ResponseTypeInChannel in channel response for slash commands.
+	ResponseTypeInChannel = "in_channel"
+	// ResponseTypeEphemeral ephemeral response for slash commands.
+	ResponseTypeEphemeral = "ephemeral"
+)
+
+// Icon is used for bot messages
+type Icon struct {
+	IconURL   string `json:"icon_url,omitempty"`
+	IconEmoji string `json:"icon_emoji,omitempty"`
+}
+
+// Edited indicates that a message has been edited.
+type Edited struct {
+	User      string `json:"user,omitempty"`
+	Timestamp string `json:"ts,omitempty"`
+}
+
+// Reply contains information about a reply for a thread
+type Reply struct {
+	User      string `json:"user,omitempty"`
+	Timestamp string `json:"ts,omitempty"`
+}
+
+// Event contains the event type
+type Event struct {
+	Type string `json:"type,omitempty"`
+}
+
+// Ping contains information about a Ping Event
+type Ping struct {
+	ID        int    `json:"id"`
+	Type      string `json:"type"`
+	Timestamp int64  `json:"timestamp"`
+}
+
+// Pong contains information about a Pong Event
+type Pong struct {
+	Type      string `json:"type"`
+	ReplyTo   int    `json:"reply_to"`
+	Timestamp int64  `json:"timestamp"`
+}
+
+// NewOutgoingMessage prepares an OutgoingMessage that the user can
+// use to send a message. Use this function to properly set the
+// messageID.
+func (rtm *RTM) NewOutgoingMessage(text string, channelID string, options ...RTMsgOption) *OutgoingMessage {
+	id := rtm.idGen.Next()
+	msg := OutgoingMessage{
+		ID:      id,
+		Type:    "message",
+		Channel: channelID,
+		Text:    text,
+	}
+	for _, option := range options {
+		option(&msg)
+	}
+	return &msg
+}
+
+// NewSubscribeUserPresence prepares an OutgoingMessage that the user can
+// use to subscribe presence events for the specified users.
+func (rtm *RTM) NewSubscribeUserPresence(ids []string) *OutgoingMessage {
+	return &OutgoingMessage{
+		Type: "presence_sub",
+		IDs:  ids,
+	}
+}
+
+// NewTypingMessage prepares an OutgoingMessage that the user can
+// use to send as a typing indicator. Use this function to properly set the
+// messageID.
+func (rtm *RTM) NewTypingMessage(channelID string) *OutgoingMessage {
+	id := rtm.idGen.Next()
+	return &OutgoingMessage{
+		ID:      id,
+		Type:    "typing",
+		Channel: channelID,
+	}
+}
+
+// RTMsgOption allows configuration of various options available for sending an RTM message
+type RTMsgOption func(*OutgoingMessage)
+
+// RTMsgOptionTS sets thead timestamp of an outgoing message in order to respond to a thread
+func RTMsgOptionTS(threadTimestamp string) RTMsgOption {
+	return func(msg *OutgoingMessage) {
+		msg.ThreadTimestamp = threadTimestamp
+	}
+}
+
+// RTMsgOptionBroadcast sets broadcast reply to channel to "true"
+func RTMsgOptionBroadcast() RTMsgOption {
+	return func(msg *OutgoingMessage) {
+		msg.ThreadBroadcast = true
+	}
+}
diff --git a/vendor/github.com/slack-go/slack/misc.go b/vendor/github.com/slack-go/slack/misc.go
new file mode 100644
index 00000000..0dcee950
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/misc.go
@@ -0,0 +1,360 @@
+package slack
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"mime"
+	"mime/multipart"
+	"net/http"
+	"net/http/httputil"
+	"net/url"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"time"
+)
+
+// SlackResponse handles parsing out errors from the web api.
+type SlackResponse struct {
+	Ok    bool   `json:"ok"`
+	Error string `json:"error"`
+}
+
+func (t SlackResponse) Err() error {
+	if t.Ok {
+		return nil
+	}
+
+	// handle pure text based responses like chat.post
+	// which while they have a slack response in their data structure
+	// it doesn't actually get set during parsing.
+	if strings.TrimSpace(t.Error) == "" {
+		return nil
+	}
+
+	return errors.New(t.Error)
+}
+
+// StatusCodeError represents an http response error.
+// type httpStatusCode interface { HTTPStatusCode() int } to handle it.
+type statusCodeError struct {
+	Code   int
+	Status string
+}
+
+func (t statusCodeError) Error() string {
+	return fmt.Sprintf("slack server error: %s", t.Status)
+}
+
+func (t statusCodeError) HTTPStatusCode() int {
+	return t.Code
+}
+
+func (t statusCodeError) Retryable() bool {
+	if t.Code >= 500 || t.Code == http.StatusTooManyRequests {
+		return true
+	}
+	return false
+}
+
+// RateLimitedError represents the rate limit respond from slack
+type RateLimitedError struct {
+	RetryAfter time.Duration
+}
+
+func (e *RateLimitedError) Error() string {
+	return fmt.Sprintf("slack rate limit exceeded, retry after %s", e.RetryAfter)
+}
+
+func (e *RateLimitedError) Retryable() bool {
+	return true
+}
+
+func fileUploadReq(ctx context.Context, path string, values url.Values, r io.Reader) (*http.Request, error) {
+	req, err := http.NewRequest("POST", path, r)
+	if err != nil {
+		return nil, err
+	}
+
+	req = req.WithContext(ctx)
+	req.URL.RawQuery = (values).Encode()
+	return req, nil
+}
+
+func downloadFile(client httpClient, token string, downloadURL string, writer io.Writer, d debug) error {
+	if downloadURL == "" {
+		return fmt.Errorf("received empty download URL")
+	}
+
+	req, err := http.NewRequest("GET", downloadURL, &bytes.Buffer{})
+	if err != nil {
+		return err
+	}
+
+	var bearer = "Bearer " + token
+	req.Header.Add("Authorization", bearer)
+	req.WithContext(context.Background())
+
+	resp, err := client.Do(req)
+	if err != nil {
+		return err
+	}
+
+	defer resp.Body.Close()
+
+	err = checkStatusCode(resp, d)
+	if err != nil {
+		return err
+	}
+
+	_, err = io.Copy(writer, resp.Body)
+
+	return err
+}
+
+func formReq(endpoint string, values url.Values) (req *http.Request, err error) {
+	if req, err = http.NewRequest("POST", endpoint, strings.NewReader(values.Encode())); err != nil {
+		return nil, err
+	}
+
+	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+	return req, nil
+}
+
+func jsonReq(endpoint string, body interface{}) (req *http.Request, err error) {
+	buffer := bytes.NewBuffer([]byte{})
+	if err = json.NewEncoder(buffer).Encode(body); err != nil {
+		return nil, err
+	}
+
+	if req, err = http.NewRequest("POST", endpoint, buffer); err != nil {
+		return nil, err
+	}
+
+	req.Header.Set("Content-Type", "application/json; charset=utf-8")
+	return req, nil
+}
+
+func parseResponseBody(body io.ReadCloser, intf interface{}, d debug) error {
+	response, err := ioutil.ReadAll(body)
+	if err != nil {
+		return err
+	}
+
+	if d.Debug() {
+		d.Debugln("parseResponseBody", string(response))
+	}
+
+	return json.Unmarshal(response, intf)
+}
+
+func postLocalWithMultipartResponse(ctx context.Context, client httpClient, method, fpath, fieldname string, values url.Values, intf interface{}, d debug) error {
+	fullpath, err := filepath.Abs(fpath)
+	if err != nil {
+		return err
+	}
+	file, err := os.Open(fullpath)
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+
+	return postWithMultipartResponse(ctx, client, method, filepath.Base(fpath), fieldname, values, file, intf, d)
+}
+
+func postWithMultipartResponse(ctx context.Context, client httpClient, path, name, fieldname string, values url.Values, r io.Reader, intf interface{}, d debug) error {
+	pipeReader, pipeWriter := io.Pipe()
+	wr := multipart.NewWriter(pipeWriter)
+	errc := make(chan error)
+	go func() {
+		defer pipeWriter.Close()
+		ioWriter, err := wr.CreateFormFile(fieldname, name)
+		if err != nil {
+			errc <- err
+			return
+		}
+		_, err = io.Copy(ioWriter, r)
+		if err != nil {
+			errc <- err
+			return
+		}
+		if err = wr.Close(); err != nil {
+			errc <- err
+			return
+		}
+	}()
+	req, err := fileUploadReq(ctx, path, values, pipeReader)
+	if err != nil {
+		return err
+	}
+	req.Header.Add("Content-Type", wr.FormDataContentType())
+	req = req.WithContext(ctx)
+	resp, err := client.Do(req)
+
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+
+	err = checkStatusCode(resp, d)
+	if err != nil {
+		return err
+	}
+
+	select {
+	case err = <-errc:
+		return err
+	default:
+		return newJSONParser(intf)(resp)
+	}
+}
+
+func doPost(ctx context.Context, client httpClient, req *http.Request, parser responseParser, d debug) error {
+	req = req.WithContext(ctx)
+	resp, err := client.Do(req)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+
+	err = checkStatusCode(resp, d)
+	if err != nil {
+		return err
+	}
+
+	return parser(resp)
+}
+
+// post JSON.
+func postJSON(ctx context.Context, client httpClient, endpoint, token string, json []byte, intf interface{}, d debug) error {
+	reqBody := bytes.NewBuffer(json)
+	req, err := http.NewRequest("POST", endpoint, reqBody)
+	if err != nil {
+		return err
+	}
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("Authorization", fmt.Sprintf("Bearer %s", token))
+
+	return doPost(ctx, client, req, newJSONParser(intf), d)
+}
+
+// post a url encoded form.
+func postForm(ctx context.Context, client httpClient, endpoint string, values url.Values, intf interface{}, d debug) error {
+	reqBody := strings.NewReader(values.Encode())
+	req, err := http.NewRequest("POST", endpoint, reqBody)
+	if err != nil {
+		return err
+	}
+	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+	return doPost(ctx, client, req, newJSONParser(intf), d)
+}
+
+func getResource(ctx context.Context, client httpClient, endpoint string, values url.Values, intf interface{}, d debug) error {
+	req, err := http.NewRequest("GET", endpoint, nil)
+	if err != nil {
+		return err
+	}
+	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+	req.URL.RawQuery = values.Encode()
+
+	return doPost(ctx, client, req, newJSONParser(intf), d)
+}
+
+func parseAdminResponse(ctx context.Context, client httpClient, method string, teamName string, values url.Values, intf interface{}, d debug) error {
+	endpoint := fmt.Sprintf(WEBAPIURLFormat, teamName, method, time.Now().Unix())
+	return postForm(ctx, client, endpoint, values, intf, d)
+}
+
+func logResponse(resp *http.Response, d debug) error {
+	if d.Debug() {
+		text, err := httputil.DumpResponse(resp, true)
+		if err != nil {
+			return err
+		}
+		d.Debugln(string(text))
+	}
+
+	return nil
+}
+
+func okJSONHandler(rw http.ResponseWriter, r *http.Request) {
+	rw.Header().Set("Content-Type", "application/json")
+	response, _ := json.Marshal(SlackResponse{
+		Ok: true,
+	})
+	rw.Write(response)
+}
+
+// timerReset safely reset a timer, see time.Timer.Reset for details.
+func timerReset(t *time.Timer, d time.Duration) {
+	if !t.Stop() {
+		<-t.C
+	}
+	t.Reset(d)
+}
+
+func checkStatusCode(resp *http.Response, d debug) error {
+	if resp.StatusCode == http.StatusTooManyRequests {
+		retry, err := strconv.ParseInt(resp.Header.Get("Retry-After"), 10, 64)
+		if err != nil {
+			return err
+		}
+		return &RateLimitedError{time.Duration(retry) * time.Second}
+	}
+
+	// Slack seems to send an HTML body along with 5xx error codes. Don't parse it.
+	if resp.StatusCode != http.StatusOK {
+		logResponse(resp, d)
+		return statusCodeError{Code: resp.StatusCode, Status: resp.Status}
+	}
+
+	return nil
+}
+
+type responseParser func(*http.Response) error
+
+func newJSONParser(dst interface{}) responseParser {
+	return func(resp *http.Response) error {
+		return json.NewDecoder(resp.Body).Decode(dst)
+	}
+}
+
+func newTextParser(dst interface{}) responseParser {
+	return func(resp *http.Response) error {
+		b, err := ioutil.ReadAll(resp.Body)
+		if err != nil {
+			return err
+		}
+
+		if !bytes.Equal(b, []byte("ok")) {
+			return errors.New(string(b))
+		}
+
+		return nil
+	}
+}
+
+func newContentTypeParser(dst interface{}) responseParser {
+	return func(req *http.Response) (err error) {
+		var (
+			ctype string
+		)
+
+		if ctype, _, err = mime.ParseMediaType(req.Header.Get("Content-Type")); err != nil {
+			return err
+		}
+
+		switch ctype {
+		case "application/json":
+			return newJSONParser(dst)(req)
+		default:
+			return newTextParser(dst)(req)
+		}
+	}
+}
diff --git a/vendor/github.com/slack-go/slack/oauth.go b/vendor/github.com/slack-go/slack/oauth.go
new file mode 100644
index 00000000..29d6dce9
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/oauth.go
@@ -0,0 +1,64 @@
+package slack
+
+import (
+	"context"
+	"net/url"
+)
+
+// OAuthResponseIncomingWebhook ...
+type OAuthResponseIncomingWebhook struct {
+	URL              string `json:"url"`
+	Channel          string `json:"channel"`
+	ChannelID        string `json:"channel_id,omitempty"`
+	ConfigurationURL string `json:"configuration_url"`
+}
+
+// OAuthResponseBot ...
+type OAuthResponseBot struct {
+	BotUserID      string `json:"bot_user_id"`
+	BotAccessToken string `json:"bot_access_token"`
+}
+
+// OAuthResponse ...
+type OAuthResponse struct {
+	AccessToken     string                       `json:"access_token"`
+	Scope           string                       `json:"scope"`
+	TeamName        string                       `json:"team_name"`
+	TeamID          string                       `json:"team_id"`
+	IncomingWebhook OAuthResponseIncomingWebhook `json:"incoming_webhook"`
+	Bot             OAuthResponseBot             `json:"bot"`
+	UserID          string                       `json:"user_id,omitempty"`
+	SlackResponse
+}
+
+// GetOAuthToken retrieves an AccessToken
+func GetOAuthToken(client httpClient, clientID, clientSecret, code, redirectURI string) (accessToken string, scope string, err error) {
+	return GetOAuthTokenContext(context.Background(), client, clientID, clientSecret, code, redirectURI)
+}
+
+// GetOAuthTokenContext retrieves an AccessToken with a custom context
+func GetOAuthTokenContext(ctx context.Context, client httpClient, clientID, clientSecret, code, redirectURI string) (accessToken string, scope string, err error) {
+	response, err := GetOAuthResponseContext(ctx, client, clientID, clientSecret, code, redirectURI)
+	if err != nil {
+		return "", "", err
+	}
+	return response.AccessToken, response.Scope, nil
+}
+
+func GetOAuthResponse(client httpClient, clientID, clientSecret, code, redirectURI string) (resp *OAuthResponse, err error) {
+	return GetOAuthResponseContext(context.Background(), client, clientID, clientSecret, code, redirectURI)
+}
+
+func GetOAuthResponseContext(ctx context.Context, client httpClient, clientID, clientSecret, code, redirectURI string) (resp *OAuthResponse, err error) {
+	values := url.Values{
+		"client_id":     {clientID},
+		"client_secret": {clientSecret},
+		"code":          {code},
+		"redirect_uri":  {redirectURI},
+	}
+	response := &OAuthResponse{}
+	if err = postForm(ctx, client, APIURL+"oauth.access", values, response, discard{}); err != nil {
+		return nil, err
+	}
+	return response, response.Err()
+}
diff --git a/vendor/github.com/slack-go/slack/pagination.go b/vendor/github.com/slack-go/slack/pagination.go
new file mode 100644
index 00000000..87dd136a
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/pagination.go
@@ -0,0 +1,20 @@
+package slack
+
+// Paging contains paging information
+type Paging struct {
+	Count int `json:"count"`
+	Total int `json:"total"`
+	Page  int `json:"page"`
+	Pages int `json:"pages"`
+}
+
+// Pagination contains pagination information
+// This is different from Paging in that it contains additional details
+type Pagination struct {
+	TotalCount int `json:"total_count"`
+	Page       int `json:"page"`
+	PerPage    int `json:"per_page"`
+	PageCount  int `json:"page_count"`
+	First      int `json:"first"`
+	Last       int `json:"last"`
+}
diff --git a/vendor/github.com/slack-go/slack/pins.go b/vendor/github.com/slack-go/slack/pins.go
new file mode 100644
index 00000000..ef97c8df
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/pins.go
@@ -0,0 +1,94 @@
+package slack
+
+import (
+	"context"
+	"errors"
+	"net/url"
+)
+
+type listPinsResponseFull struct {
+	Items  []Item
+	Paging `json:"paging"`
+	SlackResponse
+}
+
+// AddPin pins an item in a channel
+func (api *Client) AddPin(channel string, item ItemRef) error {
+	return api.AddPinContext(context.Background(), channel, item)
+}
+
+// AddPinContext pins an item in a channel with a custom context
+func (api *Client) AddPinContext(ctx context.Context, channel string, item ItemRef) error {
+	values := url.Values{
+		"channel": {channel},
+		"token":   {api.token},
+	}
+	if item.Timestamp != "" {
+		values.Set("timestamp", item.Timestamp)
+	}
+	if item.File != "" {
+		values.Set("file", item.File)
+	}
+	if item.Comment != "" {
+		values.Set("file_comment", item.Comment)
+	}
+
+	response := &SlackResponse{}
+	if err := api.postMethod(ctx, "pins.add", values, response); err != nil {
+		return err
+	}
+
+	return response.Err()
+}
+
+// RemovePin un-pins an item from a channel
+func (api *Client) RemovePin(channel string, item ItemRef) error {
+	return api.RemovePinContext(context.Background(), channel, item)
+}
+
+// RemovePinContext un-pins an item from a channel with a custom context
+func (api *Client) RemovePinContext(ctx context.Context, channel string, item ItemRef) error {
+	values := url.Values{
+		"channel": {channel},
+		"token":   {api.token},
+	}
+	if item.Timestamp != "" {
+		values.Set("timestamp", item.Timestamp)
+	}
+	if item.File != "" {
+		values.Set("file", item.File)
+	}
+	if item.Comment != "" {
+		values.Set("file_comment", item.Comment)
+	}
+
+	response := &SlackResponse{}
+	if err := api.postMethod(ctx, "pins.remove", values, response); err != nil {
+		return err
+	}
+
+	return response.Err()
+}
+
+// ListPins returns information about the items a user reacted to.
+func (api *Client) ListPins(channel string) ([]Item, *Paging, error) {
+	return api.ListPinsContext(context.Background(), channel)
+}
+
+// ListPinsContext returns information about the items a user reacted to with a custom context.
+func (api *Client) ListPinsContext(ctx context.Context, channel string) ([]Item, *Paging, error) {
+	values := url.Values{
+		"channel": {channel},
+		"token":   {api.token},
+	}
+
+	response := &listPinsResponseFull{}
+	err := api.postMethod(ctx, "pins.list", values, response)
+	if err != nil {
+		return nil, nil, err
+	}
+	if !response.Ok {
+		return nil, nil, errors.New(response.Error)
+	}
+	return response.Items, &response.Paging, nil
+}
diff --git a/vendor/github.com/slack-go/slack/reactions.go b/vendor/github.com/slack-go/slack/reactions.go
new file mode 100644
index 00000000..2a9bd42e
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/reactions.go
@@ -0,0 +1,270 @@
+package slack
+
+import (
+	"context"
+	"net/url"
+	"strconv"
+)
+
+// ItemReaction is the reactions that have happened on an item.
+type ItemReaction struct {
+	Name  string   `json:"name"`
+	Count int      `json:"count"`
+	Users []string `json:"users"`
+}
+
+// ReactedItem is an item that was reacted to, and the details of the
+// reactions.
+type ReactedItem struct {
+	Item
+	Reactions []ItemReaction
+}
+
+// GetReactionsParameters is the inputs to get reactions to an item.
+type GetReactionsParameters struct {
+	Full bool
+}
+
+// NewGetReactionsParameters initializes the inputs to get reactions to an item.
+func NewGetReactionsParameters() GetReactionsParameters {
+	return GetReactionsParameters{
+		Full: false,
+	}
+}
+
+type getReactionsResponseFull struct {
+	Type string
+	M    struct {
+		Reactions []ItemReaction
+	} `json:"message"`
+	F struct {
+		Reactions []ItemReaction
+	} `json:"file"`
+	FC struct {
+		Reactions []ItemReaction
+	} `json:"comment"`
+	SlackResponse
+}
+
+func (res getReactionsResponseFull) extractReactions() []ItemReaction {
+	switch res.Type {
+	case "message":
+		return res.M.Reactions
+	case "file":
+		return res.F.Reactions
+	case "file_comment":
+		return res.FC.Reactions
+	}
+	return []ItemReaction{}
+}
+
+const (
+	DEFAULT_REACTIONS_USER  = ""
+	DEFAULT_REACTIONS_COUNT = 100
+	DEFAULT_REACTIONS_PAGE  = 1
+	DEFAULT_REACTIONS_FULL  = false
+)
+
+// ListReactionsParameters is the inputs to find all reactions by a user.
+type ListReactionsParameters struct {
+	User  string
+	Count int
+	Page  int
+	Full  bool
+}
+
+// NewListReactionsParameters initializes the inputs to find all reactions
+// performed by a user.
+func NewListReactionsParameters() ListReactionsParameters {
+	return ListReactionsParameters{
+		User:  DEFAULT_REACTIONS_USER,
+		Count: DEFAULT_REACTIONS_COUNT,
+		Page:  DEFAULT_REACTIONS_PAGE,
+		Full:  DEFAULT_REACTIONS_FULL,
+	}
+}
+
+type listReactionsResponseFull struct {
+	Items []struct {
+		Type    string
+		Channel string
+		M       struct {
+			*Message
+		} `json:"message"`
+		F struct {
+			*File
+			Reactions []ItemReaction
+		} `json:"file"`
+		FC struct {
+			*Comment
+			Reactions []ItemReaction
+		} `json:"comment"`
+	}
+	Paging `json:"paging"`
+	SlackResponse
+}
+
+func (res listReactionsResponseFull) extractReactedItems() []ReactedItem {
+	items := make([]ReactedItem, len(res.Items))
+	for i, input := range res.Items {
+		item := ReactedItem{}
+		item.Type = input.Type
+		switch input.Type {
+		case "message":
+			item.Channel = input.Channel
+			item.Message = input.M.Message
+			item.Reactions = input.M.Reactions
+		case "file":
+			item.File = input.F.File
+			item.Reactions = input.F.Reactions
+		case "file_comment":
+			item.File = input.F.File
+			item.Comment = input.FC.Comment
+			item.Reactions = input.FC.Reactions
+		}
+		items[i] = item
+	}
+	return items
+}
+
+// AddReaction adds a reaction emoji to a message, file or file comment.
+func (api *Client) AddReaction(name string, item ItemRef) error {
+	return api.AddReactionContext(context.Background(), name, item)
+}
+
+// AddReactionContext adds a reaction emoji to a message, file or file comment with a custom context.
+func (api *Client) AddReactionContext(ctx context.Context, name string, item ItemRef) error {
+	values := url.Values{
+		"token": {api.token},
+	}
+	if name != "" {
+		values.Set("name", name)
+	}
+	if item.Channel != "" {
+		values.Set("channel", item.Channel)
+	}
+	if item.Timestamp != "" {
+		values.Set("timestamp", item.Timestamp)
+	}
+	if item.File != "" {
+		values.Set("file", item.File)
+	}
+	if item.Comment != "" {
+		values.Set("file_comment", item.Comment)
+	}
+
+	response := &SlackResponse{}
+	if err := api.postMethod(ctx, "reactions.add", values, response); err != nil {
+		return err
+	}
+
+	return response.Err()
+}
+
+// RemoveReaction removes a reaction emoji from a message, file or file comment.
+func (api *Client) RemoveReaction(name string, item ItemRef) error {
+	return api.RemoveReactionContext(context.Background(), name, item)
+}
+
+// RemoveReactionContext removes a reaction emoji from a message, file or file comment with a custom context.
+func (api *Client) RemoveReactionContext(ctx context.Context, name string, item ItemRef) error {
+	values := url.Values{
+		"token": {api.token},
+	}
+	if name != "" {
+		values.Set("name", name)
+	}
+	if item.Channel != "" {
+		values.Set("channel", item.Channel)
+	}
+	if item.Timestamp != "" {
+		values.Set("timestamp", item.Timestamp)
+	}
+	if item.File != "" {
+		values.Set("file", item.File)
+	}
+	if item.Comment != "" {
+		values.Set("file_comment", item.Comment)
+	}
+
+	response := &SlackResponse{}
+	if err := api.postMethod(ctx, "reactions.remove", values, response); err != nil {
+		return err
+	}
+
+	return response.Err()
+}
+
+// GetReactions returns details about the reactions on an item.
+func (api *Client) GetReactions(item ItemRef, params GetReactionsParameters) ([]ItemReaction, error) {
+	return api.GetReactionsContext(context.Background(), item, params)
+}
+
+// GetReactionsContext returns details about the reactions on an item with a custom context
+func (api *Client) GetReactionsContext(ctx context.Context, item ItemRef, params GetReactionsParameters) ([]ItemReaction, error) {
+	values := url.Values{
+		"token": {api.token},
+	}
+	if item.Channel != "" {
+		values.Set("channel", item.Channel)
+	}
+	if item.Timestamp != "" {
+		values.Set("timestamp", item.Timestamp)
+	}
+	if item.File != "" {
+		values.Set("file", item.File)
+	}
+	if item.Comment != "" {
+		values.Set("file_comment", item.Comment)
+	}
+	if params.Full != DEFAULT_REACTIONS_FULL {
+		values.Set("full", strconv.FormatBool(params.Full))
+	}
+
+	response := &getReactionsResponseFull{}
+	if err := api.postMethod(ctx, "reactions.get", values, response); err != nil {
+		return nil, err
+	}
+
+	if err := response.Err(); err != nil {
+		return nil, err
+	}
+
+	return response.extractReactions(), nil
+}
+
+// ListReactions returns information about the items a user reacted to.
+func (api *Client) ListReactions(params ListReactionsParameters) ([]ReactedItem, *Paging, error) {
+	return api.ListReactionsContext(context.Background(), params)
+}
+
+// ListReactionsContext returns information about the items a user reacted to with a custom context.
+func (api *Client) ListReactionsContext(ctx context.Context, params ListReactionsParameters) ([]ReactedItem, *Paging, error) {
+	values := url.Values{
+		"token": {api.token},
+	}
+	if params.User != DEFAULT_REACTIONS_USER {
+		values.Add("user", params.User)
+	}
+	if params.Count != DEFAULT_REACTIONS_COUNT {
+		values.Add("count", strconv.Itoa(params.Count))
+	}
+	if params.Page != DEFAULT_REACTIONS_PAGE {
+		values.Add("page", strconv.Itoa(params.Page))
+	}
+	if params.Full != DEFAULT_REACTIONS_FULL {
+		values.Add("full", strconv.FormatBool(params.Full))
+	}
+
+	response := &listReactionsResponseFull{}
+	err := api.postMethod(ctx, "reactions.list", values, response)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	if err := response.Err(); err != nil {
+		return nil, nil, err
+	}
+
+	return response.extractReactedItems(), &response.Paging, nil
+}
diff --git a/vendor/github.com/slack-go/slack/reminders.go b/vendor/github.com/slack-go/slack/reminders.go
new file mode 100644
index 00000000..9b905387
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/reminders.go
@@ -0,0 +1,75 @@
+package slack
+
+import (
+	"context"
+	"net/url"
+	"time"
+)
+
+type Reminder struct {
+	ID         string    `json:"id"`
+	Creator    string    `json:"creator"`
+	User       string    `json:"user"`
+	Text       string    `json:"text"`
+	Recurring  bool      `json:"recurring"`
+	Time       time.Time `json:"time"`
+	CompleteTS int       `json:"complete_ts"`
+}
+
+type reminderResp struct {
+	SlackResponse
+	Reminder Reminder `json:"reminder"`
+}
+
+func (api *Client) doReminder(ctx context.Context, path string, values url.Values) (*Reminder, error) {
+	response := &reminderResp{}
+	if err := api.postMethod(ctx, path, values, response); err != nil {
+		return nil, err
+	}
+	return &response.Reminder, response.Err()
+}
+
+// AddChannelReminder adds a reminder for a channel.
+//
+// See https://api.slack.com/methods/reminders.add (NOTE: the ability to set
+// reminders on a channel is currently undocumented but has been tested to
+// work)
+func (api *Client) AddChannelReminder(channelID, text, time string) (*Reminder, error) {
+	values := url.Values{
+		"token":   {api.token},
+		"text":    {text},
+		"time":    {time},
+		"channel": {channelID},
+	}
+	return api.doReminder(context.Background(), "reminders.add", values)
+}
+
+// AddUserReminder adds a reminder for a user.
+//
+// See https://api.slack.com/methods/reminders.add (NOTE: the ability to set
+// reminders on a channel is currently undocumented but has been tested to
+// work)
+func (api *Client) AddUserReminder(userID, text, time string) (*Reminder, error) {
+	values := url.Values{
+		"token": {api.token},
+		"text":  {text},
+		"time":  {time},
+		"user":  {userID},
+	}
+	return api.doReminder(context.Background(), "reminders.add", values)
+}
+
+// DeleteReminder deletes an existing reminder.
+//
+// See https://api.slack.com/methods/reminders.delete
+func (api *Client) DeleteReminder(id string) error {
+	values := url.Values{
+		"token":    {api.token},
+		"reminder": {id},
+	}
+	response := &SlackResponse{}
+	if err := api.postMethod(context.Background(), "reminders.delete", values, response); err != nil {
+		return err
+	}
+	return response.Err()
+}
diff --git a/vendor/github.com/slack-go/slack/rtm.go b/vendor/github.com/slack-go/slack/rtm.go
new file mode 100644
index 00000000..ef6ba343
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/rtm.go
@@ -0,0 +1,131 @@
+package slack
+
+import (
+	"context"
+	"net/url"
+	"sync"
+	"time"
+
+	"github.com/gorilla/websocket"
+)
+
+const (
+	websocketDefaultTimeout = 10 * time.Second
+	defaultPingInterval     = 30 * time.Second
+)
+
+const (
+	rtmEventTypeAck                 = ""
+	rtmEventTypeHello               = "hello"
+	rtmEventTypeGoodbye             = "goodbye"
+	rtmEventTypePong                = "pong"
+	rtmEventTypeDesktopNotification = "desktop_notification"
+)
+
+// StartRTM calls the "rtm.start" endpoint and returns the provided URL and the full Info block.
+//
+// To have a fully managed Websocket connection, use `NewRTM`, and call `ManageConnection()` on it.
+func (api *Client) StartRTM() (info *Info, websocketURL string, err error) {
+	ctx, cancel := context.WithTimeout(context.Background(), websocketDefaultTimeout)
+	defer cancel()
+
+	return api.StartRTMContext(ctx)
+}
+
+// StartRTMContext calls the "rtm.start" endpoint and returns the provided URL and the full Info block with a custom context.
+//
+// To have a fully managed Websocket connection, use `NewRTM`, and call `ManageConnection()` on it.
+func (api *Client) StartRTMContext(ctx context.Context) (info *Info, websocketURL string, err error) {
+	response := &infoResponseFull{}
+	err = api.postMethod(ctx, "rtm.start", url.Values{"token": {api.token}}, response)
+	if err != nil {
+		return nil, "", err
+	}
+
+	api.Debugln("Using URL:", response.Info.URL)
+	return &response.Info, response.Info.URL, response.Err()
+}
+
+// ConnectRTM calls the "rtm.connect" endpoint and returns the provided URL and the compact Info block.
+//
+// To have a fully managed Websocket connection, use `NewRTM`, and call `ManageConnection()` on it.
+func (api *Client) ConnectRTM() (info *Info, websocketURL string, err error) {
+	ctx, cancel := context.WithTimeout(context.Background(), websocketDefaultTimeout)
+	defer cancel()
+
+	return api.ConnectRTMContext(ctx)
+}
+
+// ConnectRTMContext calls the "rtm.connect" endpoint and returns the
+// provided URL and the compact Info block with a custom context.
+//
+// To have a fully managed Websocket connection, use `NewRTM`, and call `ManageConnection()` on it.
+func (api *Client) ConnectRTMContext(ctx context.Context) (info *Info, websocketURL string, err error) {
+	response := &infoResponseFull{}
+	err = api.postMethod(ctx, "rtm.connect", url.Values{"token": {api.token}}, response)
+	if err != nil {
+		api.Debugf("Failed to connect to RTM: %s", err)
+		return nil, "", err
+	}
+
+	api.Debugln("Using URL:", response.Info.URL)
+	return &response.Info, response.Info.URL, response.Err()
+}
+
+// RTMOption options for the managed RTM.
+type RTMOption func(*RTM)
+
+// RTMOptionUseStart as of 11th July 2017 you should prefer setting this to false, see:
+// https://api.slack.com/changelog/2017-04-start-using-rtm-connect-and-stop-using-rtm-start
+func RTMOptionUseStart(b bool) RTMOption {
+	return func(rtm *RTM) {
+		rtm.useRTMStart = b
+	}
+}
+
+// RTMOptionDialer takes a gorilla websocket Dialer and uses it as the
+// Dialer when opening the websocket for the RTM connection.
+func RTMOptionDialer(d *websocket.Dialer) RTMOption {
+	return func(rtm *RTM) {
+		rtm.dialer = d
+	}
+}
+
+// RTMOptionPingInterval determines how often to deliver a ping message to slack.
+func RTMOptionPingInterval(d time.Duration) RTMOption {
+	return func(rtm *RTM) {
+		rtm.pingInterval = d
+		rtm.resetDeadman()
+	}
+}
+
+// RTMOptionConnParams installs parameters to embed into the connection URL.
+func RTMOptionConnParams(connParams url.Values) RTMOption {
+	return func(rtm *RTM) {
+		rtm.connParams = connParams
+	}
+}
+
+// NewRTM returns a RTM, which provides a fully managed connection to
+// Slack's websocket-based Real-Time Messaging protocol.
+func (api *Client) NewRTM(options ...RTMOption) *RTM {
+	result := &RTM{
+		Client:           *api,
+		IncomingEvents:   make(chan RTMEvent, 50),
+		outgoingMessages: make(chan OutgoingMessage, 20),
+		pingInterval:     defaultPingInterval,
+		pingDeadman:      time.NewTimer(deadmanDuration(defaultPingInterval)),
+		killChannel:      make(chan bool),
+		disconnected:     make(chan struct{}),
+		disconnectedm:    &sync.Once{},
+		forcePing:        make(chan bool),
+		idGen:            NewSafeID(1),
+		mu:               &sync.Mutex{},
+	}
+
+	for _, opt := range options {
+		opt(result)
+	}
+
+	return result
+}
diff --git a/vendor/github.com/slack-go/slack/search.go b/vendor/github.com/slack-go/slack/search.go
new file mode 100644
index 00000000..de6b40ac
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/search.go
@@ -0,0 +1,156 @@
+package slack
+
+import (
+	"context"
+	"net/url"
+	"strconv"
+)
+
+const (
+	DEFAULT_SEARCH_SORT      = "score"
+	DEFAULT_SEARCH_SORT_DIR  = "desc"
+	DEFAULT_SEARCH_HIGHLIGHT = false
+	DEFAULT_SEARCH_COUNT     = 20
+	DEFAULT_SEARCH_PAGE      = 1
+)
+
+type SearchParameters struct {
+	Sort          string
+	SortDirection string
+	Highlight     bool
+	Count         int
+	Page          int
+}
+
+type CtxChannel struct {
+	ID                 string `json:"id"`
+	Name               string `json:"name"`
+	IsExtShared        bool   `json:"is_ext_shared"`
+	IsMPIM             bool   `json:"is_mpim"`
+	ISOrgShared        bool   `json:"is_org_shared"`
+	IsPendingExtShared bool   `json:"is_pending_ext_shared"`
+	IsPrivate          bool   `json:"is_private"`
+	IsShared           bool   `json:"is_shared"`
+}
+
+type CtxMessage struct {
+	User      string `json:"user"`
+	Username  string `json:"username"`
+	Text      string `json:"text"`
+	Timestamp string `json:"ts"`
+	Type      string `json:"type"`
+}
+
+type SearchMessage struct {
+	Type        string       `json:"type"`
+	Channel     CtxChannel   `json:"channel"`
+	User        string       `json:"user"`
+	Username    string       `json:"username"`
+	Timestamp   string       `json:"ts"`
+	Blocks      Blocks       `json:"blocks,omitempty"`
+	Text        string       `json:"text"`
+	Permalink   string       `json:"permalink"`
+	Attachments []Attachment `json:"attachments"`
+	Previous    CtxMessage   `json:"previous"`
+	Previous2   CtxMessage   `json:"previous_2"`
+	Next        CtxMessage   `json:"next"`
+	Next2       CtxMessage   `json:"next_2"`
+}
+
+type SearchMessages struct {
+	Matches    []SearchMessage `json:"matches"`
+	Paging     `json:"paging"`
+	Pagination `json:"pagination"`
+	Total      int `json:"total"`
+}
+
+type SearchFiles struct {
+	Matches    []File `json:"matches"`
+	Paging     `json:"paging"`
+	Pagination `json:"pagination"`
+	Total      int `json:"total"`
+}
+
+type searchResponseFull struct {
+	Query          string `json:"query"`
+	SearchMessages `json:"messages"`
+	SearchFiles    `json:"files"`
+	SlackResponse
+}
+
+func NewSearchParameters() SearchParameters {
+	return SearchParameters{
+		Sort:          DEFAULT_SEARCH_SORT,
+		SortDirection: DEFAULT_SEARCH_SORT_DIR,
+		Highlight:     DEFAULT_SEARCH_HIGHLIGHT,
+		Count:         DEFAULT_SEARCH_COUNT,
+		Page:          DEFAULT_SEARCH_PAGE,
+	}
+}
+
+func (api *Client) _search(ctx context.Context, path, query string, params SearchParameters, files, messages bool) (response *searchResponseFull, error error) {
+	values := url.Values{
+		"token": {api.token},
+		"query": {query},
+	}
+	if params.Sort != DEFAULT_SEARCH_SORT {
+		values.Add("sort", params.Sort)
+	}
+	if params.SortDirection != DEFAULT_SEARCH_SORT_DIR {
+		values.Add("sort_dir", params.SortDirection)
+	}
+	if params.Highlight != DEFAULT_SEARCH_HIGHLIGHT {
+		values.Add("highlight", strconv.Itoa(1))
+	}
+	if params.Count != DEFAULT_SEARCH_COUNT {
+		values.Add("count", strconv.Itoa(params.Count))
+	}
+	if params.Page != DEFAULT_SEARCH_PAGE {
+		values.Add("page", strconv.Itoa(params.Page))
+	}
+
+	response = &searchResponseFull{}
+	err := api.postMethod(ctx, path, values, response)
+	if err != nil {
+		return nil, err
+	}
+
+	return response, response.Err()
+
+}
+
+func (api *Client) Search(query string, params SearchParameters) (*SearchMessages, *SearchFiles, error) {
+	return api.SearchContext(context.Background(), query, params)
+}
+
+func (api *Client) SearchContext(ctx context.Context, query string, params SearchParameters) (*SearchMessages, *SearchFiles, error) {
+	response, err := api._search(ctx, "search.all", query, params, true, true)
+	if err != nil {
+		return nil, nil, err
+	}
+	return &response.SearchMessages, &response.SearchFiles, nil
+}
+
+func (api *Client) SearchFiles(query string, params SearchParameters) (*SearchFiles, error) {
+	return api.SearchFilesContext(context.Background(), query, params)
+}
+
+func (api *Client) SearchFilesContext(ctx context.Context, query string, params SearchParameters) (*SearchFiles, error) {
+	response, err := api._search(ctx, "search.files", query, params, true, false)
+	if err != nil {
+		return nil, err
+	}
+	return &response.SearchFiles, nil
+}
+
+func (api *Client) SearchMessages(query string, params SearchParameters) (*SearchMessages, error) {
+	return api.SearchMessagesContext(context.Background(), query, params)
+}
+
+func (api *Client) SearchMessagesContext(ctx context.Context, query string, params SearchParameters) (*SearchMessages, error) {
+	response, err := api._search(ctx, "search.messages", query, params, false, true)
+	if err != nil {
+		return nil, err
+	}
+	return &response.SearchMessages, nil
+}
diff --git a/vendor/github.com/slack-go/slack/security.go b/vendor/github.com/slack-go/slack/security.go
new file mode 100644
index 00000000..dbe8fb2d
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/security.go
@@ -0,0 +1,100 @@
+package slack
+
+import (
+	"crypto/hmac"
+	"crypto/sha256"
+	"encoding/hex"
+	"fmt"
+	"hash"
+	"net/http"
+	"strconv"
+	"strings"
+	"time"
+)
+
+// Signature headers
+const (
+	hSignature = "X-Slack-Signature"
+	hTimestamp = "X-Slack-Request-Timestamp"
+)
+
+// SecretsVerifier contains the information needed to verify that the request comes from Slack
+type SecretsVerifier struct {
+	signature []byte
+	hmac      hash.Hash
+}
+
+func unsafeSignatureVerifier(header http.Header, secret string) (_ SecretsVerifier, err error) {
+	var (
+		bsignature []byte
+	)
+
+	signature := header.Get(hSignature)
+	stimestamp := header.Get(hTimestamp)
+
+	if signature == "" || stimestamp == "" {
+		return SecretsVerifier{}, ErrMissingHeaders
+	}
+
+	if bsignature, err = hex.DecodeString(strings.TrimPrefix(signature, "v0=")); err != nil {
+		return SecretsVerifier{}, err
+	}
+
+	hash := hmac.New(sha256.New, []byte(secret))
+	if _, err = hash.Write([]byte(fmt.Sprintf("v0:%s:", stimestamp))); err != nil {
+		return SecretsVerifier{}, err
+	}
+
+	return SecretsVerifier{
+		signature: bsignature,
+		hmac:      hash,
+	}, nil
+}
+
+// NewSecretsVerifier returns a SecretsVerifier object in exchange for an http.Header object and signing secret
+func NewSecretsVerifier(header http.Header, secret string) (sv SecretsVerifier, err error) {
+	var (
+		timestamp int64
+	)
+
+	stimestamp := header.Get(hTimestamp)
+
+	if sv, err = unsafeSignatureVerifier(header, secret); err != nil {
+		return SecretsVerifier{}, err
+	}
+
+	if timestamp, err = strconv.ParseInt(stimestamp, 10, 64); err != nil {
+		return SecretsVerifier{}, err
+	}
+
+	diff := absDuration(time.Since(time.Unix(timestamp, 0)))
+	if diff > 5*time.Minute {
+		return SecretsVerifier{}, ErrExpiredTimestamp
+	}
+
+	return sv, err
+}
+
+func (v *SecretsVerifier) Write(body []byte) (n int, err error) {
+	return v.hmac.Write(body)
+}
+
+// Ensure compares the signature sent from Slack with the actual computed hash to judge validity
+func (v SecretsVerifier) Ensure() error {
+	computed := v.hmac.Sum(nil)
+	// use hmac.Equal prevent leaking timing information.
+	if hmac.Equal(computed, v.signature) {
+		return nil
+	}
+
+	return fmt.Errorf("Expected signing signature: %s, but computed: %s", hex.EncodeToString(v.signature), hex.EncodeToString(computed))
+}
+
+func abs64(n int64) int64 {
+	y := n >> 63
+	return (n ^ y) - y
+}
+
+func absDuration(n time.Duration) time.Duration {
+	return time.Duration(abs64(int64(n)))
+}
diff --git a/vendor/github.com/slack-go/slack/slack.go b/vendor/github.com/slack-go/slack/slack.go
new file mode 100644
index 00000000..d342a3e8
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/slack.go
@@ -0,0 +1,153 @@
+package slack
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"net/http"
+	"net/url"
+	"os"
+)
+
+const (
+	// APIURL of the slack api.
+	APIURL = "https://slack.com/api/"
+	// WEBAPIURLFormat ...
+	WEBAPIURLFormat = "https://%s.slack.com/api/users.admin.%s?t=%d"
+)
+
+// httpClient defines the minimal interface needed for an http.Client to be implemented.
+type httpClient interface {
+	Do(*http.Request) (*http.Response, error)
+}
+
+// ResponseMetadata holds pagination metadata
+type ResponseMetadata struct {
+	Cursor string `json:"next_cursor"`
+}
+
+func (t *ResponseMetadata) initialize() *ResponseMetadata {
+	if t != nil {
+		return t
+	}
+
+	return &ResponseMetadata{}
+}
+
+// AuthTestResponse ...
+type AuthTestResponse struct {
+	URL    string `json:"url"`
+	Team   string `json:"team"`
+	User   string `json:"user"`
+	TeamID string `json:"team_id"`
+	UserID string `json:"user_id"`
+	// EnterpriseID is only returned when an enterprise id present
+	EnterpriseID string `json:"enterprise_id,omitempty"`
+}
+
+type authTestResponseFull struct {
+	SlackResponse
+	AuthTestResponse
+}
+
+// Client for the slack api.
+type ParamOption func(*url.Values)
+
+type Client struct {
+	token      string
+	endpoint   string
+	debug      bool
+	log        ilogger
+	httpclient httpClient
+}
+
+// Option defines an option for a Client
+type Option func(*Client)
+
+// OptionHTTPClient - provide a custom http client to the slack client.
+func OptionHTTPClient(client httpClient) func(*Client) {
+	return func(c *Client) {
+		c.httpclient = client
+	}
+}
+
+// OptionDebug enable debugging for the client
+func OptionDebug(b bool) func(*Client) {
+	return func(c *Client) {
+		c.debug = b
+	}
+}
+
+// OptionLog set logging for client.
+func OptionLog(l logger) func(*Client) {
+	return func(c *Client) {
+		c.log = internalLog{logger: l}
+	}
+}
+
+// OptionAPIURL set the url for the client. only useful for testing.
+func OptionAPIURL(u string) func(*Client) {
+	return func(c *Client) { c.endpoint = u }
+}
+
+// New builds a slack client from the provided token and options.
+func New(token string, options ...Option) *Client {
+	s := &Client{
+		token:      token,
+		endpoint:   APIURL,
+		httpclient: &http.Client{},
+		log:        log.New(os.Stderr, "slack-go/slack", log.LstdFlags|log.Lshortfile),
+	}
+
+	for _, opt := range options {
+		opt(s)
+	}
+
+	return s
+}
+
+// AuthTest tests if the user is able to do authenticated requests or not
+func (api *Client) AuthTest() (response *AuthTestResponse, error error) {
+	return api.AuthTestContext(context.Background())
+}
+
+// AuthTestContext tests if the user is able to do authenticated requests or not with a custom context
+func (api *Client) AuthTestContext(ctx context.Context) (response *AuthTestResponse, err error) {
+	api.Debugf("Challenging auth...")
+	responseFull := &authTestResponseFull{}
+	err = api.postMethod(ctx, "auth.test", url.Values{"token": {api.token}}, responseFull)
+	if err != nil {
+		return nil, err
+	}
+
+	return &responseFull.AuthTestResponse, responseFull.Err()
+}
+
+// Debugf print a formatted debug line.
+func (api *Client) Debugf(format string, v ...interface{}) {
+	if api.debug {
+		api.log.Output(2, fmt.Sprintf(format, v...))
+	}
+}
+
+// Debugln print a debug line.
+func (api *Client) Debugln(v ...interface{}) {
+	if api.debug {
+		api.log.Output(2, fmt.Sprintln(v...))
+	}
+}
+
+// Debug returns if debug is enabled.
+func (api *Client) Debug() bool {
+	return api.debug
+}
+
+// post to a slack web method.
+func (api *Client) postMethod(ctx context.Context, path string, values url.Values, intf interface{}) error {
+	return postForm(ctx, api.httpclient, api.endpoint+path, values, intf, api)
+}
+
+// get a slack web method.
+func (api *Client) getMethod(ctx context.Context, path string, values url.Values, intf interface{}) error {
+	return getResource(ctx, api.httpclient, api.endpoint+path, values, intf, api)
+}
diff --git a/vendor/github.com/slack-go/slack/slackutilsx/slackutilsx.go b/vendor/github.com/slack-go/slack/slackutilsx/slackutilsx.go
new file mode 100644
index 00000000..1f7b2b8c
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/slackutilsx/slackutilsx.go
@@ -0,0 +1,62 @@
+// Package slackutilsx is a utility package that doesn't promise API stability.
+// its for experimental functionality and utilities.
+package slackutilsx
+
+import (
+	"strings"
+	"unicode/utf8"
+)
+
+// ChannelType the type of channel based on the channelID
+type ChannelType int
+
+func (t ChannelType) String() string {
+	switch t {
+	case CTypeDM:
+		return "Direct"
+	case CTypeGroup:
+		return "Group"
+	case CTypeChannel:
+		return "Channel"
+	default:
+		return "Unknown"
+	}
+}
+
+const (
+	// CTypeUnknown represents channels we cannot properly detect.
+	CTypeUnknown ChannelType = iota
+	// CTypeDM is a private channel between two slack users.
+	CTypeDM
+	// CTypeGroup is a group channel.
+	CTypeGroup
+	// CTypeChannel is a public channel.
+	CTypeChannel
+)
+
+// DetectChannelType converts a channelID to a ChannelType.
+// channelID must not be empty. However, if it is empty, the channel type will default to Unknown.
+func DetectChannelType(channelID string) ChannelType {
+	// intentionally ignore the error and just default to CTypeUnknown
+	switch r, _ := utf8.DecodeRuneInString(channelID); r {
+	case 'C':
+		return CTypeChannel
+	case 'G':
+		return CTypeGroup
+	case 'D':
+		return CTypeDM
+	default:
+		return CTypeUnknown
+	}
+}
+
+// EscapeMessage text
+func EscapeMessage(message string) string {
+	replacer := strings.NewReplacer("&", "&amp;", "<", "&lt;", ">", "&gt;")
+	return replacer.Replace(message)
+}
+
+// Retryable errors return true.
+type Retryable interface {
+	Retryable() bool
+}
diff --git a/vendor/github.com/slack-go/slack/slash.go b/vendor/github.com/slack-go/slack/slash.go
new file mode 100644
index 00000000..f62065a2
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/slash.go
@@ -0,0 +1,53 @@
+package slack
+
+import (
+	"net/http"
+)
+
+// SlashCommand contains information about a request of the slash command
+type SlashCommand struct {
+	Token          string `json:"token"`
+	TeamID         string `json:"team_id"`
+	TeamDomain     string `json:"team_domain"`
+	EnterpriseID   string `json:"enterprise_id,omitempty"`
+	EnterpriseName string `json:"enterprise_name,omitempty"`
+	ChannelID      string `json:"channel_id"`
+	ChannelName    string `json:"channel_name"`
+	UserID         string `json:"user_id"`
+	UserName       string `json:"user_name"`
+	Command        string `json:"command"`
+	Text           string `json:"text"`
+	ResponseURL    string `json:"response_url"`
+	TriggerID      string `json:"trigger_id"`
+}
+
+// SlashCommandParse will parse the request of the slash command
+func SlashCommandParse(r *http.Request) (s SlashCommand, err error) {
+	if err = r.ParseForm(); err != nil {
+		return s, err
+	}
+	s.Token = r.PostForm.Get("token")
+	s.TeamID = r.PostForm.Get("team_id")
+	s.TeamDomain = r.PostForm.Get("team_domain")
+	s.EnterpriseID = r.PostForm.Get("enterprise_id")
+	s.EnterpriseName = r.PostForm.Get("enterprise_name")
+	s.ChannelID = r.PostForm.Get("channel_id")
+	s.ChannelName = r.PostForm.Get("channel_name")
+	s.UserID = r.PostForm.Get("user_id")
+	s.UserName = r.PostForm.Get("user_name")
+	s.Command = r.PostForm.Get("command")
+	s.Text = r.PostForm.Get("text")
+	s.ResponseURL = r.PostForm.Get("response_url")
+	s.TriggerID = r.PostForm.Get("trigger_id")
+	return s, nil
+}
+
+// ValidateToken validates verificationTokens
+func (s SlashCommand) ValidateToken(verificationTokens ...string) bool {
+	for _, token := range verificationTokens {
+		if s.Token == token {
+			return true
+		}
+	}
+	return false
+}
diff --git a/vendor/github.com/slack-go/slack/stars.go b/vendor/github.com/slack-go/slack/stars.go
new file mode 100644
index 00000000..52967604
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/stars.go
@@ -0,0 +1,263 @@
+package slack
+
+import (
+	"context"
+	"net/url"
+	"strconv"
+	"time"
+)
+
+const (
+	DEFAULT_STARS_USER  = ""
+	DEFAULT_STARS_COUNT = 100
+	DEFAULT_STARS_PAGE  = 1
+)
+
+type StarsParameters struct {
+	User  string
+	Count int
+	Page  int
+}
+
+type StarredItem Item
+
+type listResponseFull struct {
+	Items  []Item `json:"items"`
+	Paging `json:"paging"`
+	SlackResponse
+}
+
+// NewStarsParameters initialises StarsParameters with default values
+func NewStarsParameters() StarsParameters {
+	return StarsParameters{
+		User:  DEFAULT_STARS_USER,
+		Count: DEFAULT_STARS_COUNT,
+		Page:  DEFAULT_STARS_PAGE,
+	}
+}
+
+// AddStar stars an item in a channel
+func (api *Client) AddStar(channel string, item ItemRef) error {
+	return api.AddStarContext(context.Background(), channel, item)
+}
+
+// AddStarContext stars an item in a channel with a custom context
+func (api *Client) AddStarContext(ctx context.Context, channel string, item ItemRef) error {
+	values := url.Values{
+		"channel": {channel},
+		"token":   {api.token},
+	}
+	if item.Timestamp != "" {
+		values.Set("timestamp", item.Timestamp)
+	}
+	if item.File != "" {
+		values.Set("file", item.File)
+	}
+	if item.Comment != "" {
+		values.Set("file_comment", item.Comment)
+	}
+
+	response := &SlackResponse{}
+	if err := api.postMethod(ctx, "stars.add", values, response); err != nil {
+		return err
+	}
+
+	return response.Err()
+}
+
+// RemoveStar removes a starred item from a channel
+func (api *Client) RemoveStar(channel string, item ItemRef) error {
+	return api.RemoveStarContext(context.Background(), channel, item)
+}
+
+// RemoveStarContext removes a starred item from a channel with a custom context
+func (api *Client) RemoveStarContext(ctx context.Context, channel string, item ItemRef) error {
+	values := url.Values{
+		"channel": {channel},
+		"token":   {api.token},
+	}
+	if item.Timestamp != "" {
+		values.Set("timestamp", item.Timestamp)
+	}
+	if item.File != "" {
+		values.Set("file", item.File)
+	}
+	if item.Comment != "" {
+		values.Set("file_comment", item.Comment)
+	}
+
+	response := &SlackResponse{}
+	if err := api.postMethod(ctx, "stars.remove", values, response); err != nil {
+		return err
+	}
+
+	return response.Err()
+}
+
+// ListStars returns information about the stars a user added
+func (api *Client) ListStars(params StarsParameters) ([]Item, *Paging, error) {
+	return api.ListStarsContext(context.Background(), params)
+}
+
+// ListStarsContext returns information about the stars a user added with a custom context
+func (api *Client) ListStarsContext(ctx context.Context, params StarsParameters) ([]Item, *Paging, error) {
+	values := url.Values{
+		"token": {api.token},
+	}
+	if params.User != DEFAULT_STARS_USER {
+		values.Add("user", params.User)
+	}
+	if params.Count != DEFAULT_STARS_COUNT {
+		values.Add("count", strconv.Itoa(params.Count))
+	}
+	if params.Page != DEFAULT_STARS_PAGE {
+		values.Add("page", strconv.Itoa(params.Page))
+	}
+
+	response := &listResponseFull{}
+	err := api.postMethod(ctx, "stars.list", values, response)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	if err := response.Err(); err != nil {
+		return nil, nil, err
+	}
+
+	return response.Items, &response.Paging, nil
+}
+
+// GetStarred returns a list of StarredItem items.
+//
+// The user then has to iterate over them and figure out what they should
+// be looking at according to what is in the Type.
+//    for _, item := range items {
+//        switch c.Type {
+//        case "file_comment":
+//            log.Println(c.Comment)
+//        case "file":
+//             ...
+//
+//    }
+// This function still exists to maintain backwards compatibility.
+// I exposed it as returning []StarredItem, so it shall stay as StarredItem
+func (api *Client) GetStarred(params StarsParameters) ([]StarredItem, *Paging, error) {
+	return api.GetStarredContext(context.Background(), params)
+}
+
+// GetStarredContext returns a list of StarredItem items with a custom context
+//
+// For more details see GetStarred
+func (api *Client) GetStarredContext(ctx context.Context, params StarsParameters) ([]StarredItem, *Paging, error) {
+	items, paging, err := api.ListStarsContext(ctx, params)
+	if err != nil {
+		return nil, nil, err
+	}
+	starredItems := make([]StarredItem, len(items))
+	for i, item := range items {
+		starredItems[i] = StarredItem(item)
+	}
+	return starredItems, paging, nil
+}
+
+type listResponsePaginated struct {
+	Items []Item `json:"items"`
+	SlackResponse
+	Metadata ResponseMetadata `json:"response_metadata"`
+}
+
+// StarredItemPagination allows for paginating over the starred items
+type StarredItemPagination struct {
+	Items        []Item
+	limit        int
+	previousResp *ResponseMetadata
+	c            *Client
+}
+
+// ListStarsOption options for the GetUsers method call.
+type ListStarsOption func(*StarredItemPagination)
+
+// ListAllStars returns the complete list of starred items
+func (api *Client) ListAllStars() ([]Item, error) {
+	return api.ListAllStarsContext(context.Background())
+}
+
+// ListAllStarsContext returns the list of users (with their detailed information) with a custom context
+func (api *Client) ListAllStarsContext(ctx context.Context) (results []Item, err error) {
+	p := api.ListStarsPaginated()
+	for err == nil {
+		p, err = p.next(ctx)
+		if err == nil {
+			results = append(results, p.Items...)
+		} else if rateLimitedError, ok := err.(*RateLimitedError); ok {
+			select {
+			case <-ctx.Done():
+				err = ctx.Err()
+			case <-time.After(rateLimitedError.RetryAfter):
+				err = nil
+			}
+		}
+	}
+
+	return results, p.failure(err)
+}
+
+// ListStarsPaginated fetches users in a paginated fashion, see ListStarsPaginationContext for usage.
+func (api *Client) ListStarsPaginated(options ...ListStarsOption) StarredItemPagination {
+	return newStarPagination(api, options...)
+}
+
+func newStarPagination(c *Client, options ...ListStarsOption) (sip StarredItemPagination) {
+	sip = StarredItemPagination{
+		c:     c,
+		limit: 200, // per slack api documentation.
+	}
+
+	for _, opt := range options {
+		opt(&sip)
+	}
+
+	return sip
+}
+
+// done checks if the pagination has completed
+func (StarredItemPagination) done(err error) bool {
+	return err == errPaginationComplete
+}
+
+// done checks if pagination failed.
+func (t StarredItemPagination) failure(err error) error {
+	if t.done(err) {
+		return nil
+	}
+
+	return err
+}
+
+// next gets the next list of starred items based on the cursor value
+func (t StarredItemPagination) next(ctx context.Context) (_ StarredItemPagination, err error) {
+	var (
+		resp *listResponsePaginated
+	)
+
+	if t.c == nil || (t.previousResp != nil && t.previousResp.Cursor == "") {
+		return t, errPaginationComplete
+	}
+
+	t.previousResp = t.previousResp.initialize()
+
+	values := url.Values{
+		"limit":  {strconv.Itoa(t.limit)},
+		"token":  {t.c.token},
+		"cursor": {t.previousResp.Cursor},
+	}
+
+	if err = t.c.postMethod(ctx, "stars.list", values, &resp); err != nil {
+		return t, err
+	}
+
+	t.previousResp = &resp.Metadata
+	t.Items = resp.Items
+
+	return t, nil
+}
diff --git a/vendor/github.com/slack-go/slack/team.go b/vendor/github.com/slack-go/slack/team.go
new file mode 100644
index 00000000..029e2b5b
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/team.go
@@ -0,0 +1,167 @@
+package slack
+
+import (
+	"context"
+	"net/url"
+	"strconv"
+)
+
+const (
+	DEFAULT_LOGINS_COUNT = 100
+	DEFAULT_LOGINS_PAGE  = 1
+)
+
+type TeamResponse struct {
+	Team TeamInfo `json:"team"`
+	SlackResponse
+}
+
+type TeamInfo struct {
+	ID          string                 `json:"id"`
+	Name        string                 `json:"name"`
+	Domain      string                 `json:"domain"`
+	EmailDomain string                 `json:"email_domain"`
+	Icon        map[string]interface{} `json:"icon"`
+}
+
+type LoginResponse struct {
+	Logins []Login `json:"logins"`
+	Paging `json:"paging"`
+	SlackResponse
+}
+
+type Login struct {
+	UserID    string `json:"user_id"`
+	Username  string `json:"username"`
+	DateFirst int    `json:"date_first"`
+	DateLast  int    `json:"date_last"`
+	Count     int    `json:"count"`
+	IP        string `json:"ip"`
+	UserAgent string `json:"user_agent"`
+	ISP       string `json:"isp"`
+	Country   string `json:"country"`
+	Region    string `json:"region"`
+}
+
+type BillableInfoResponse struct {
+	BillableInfo map[string]BillingActive `json:"billable_info"`
+	SlackResponse
+}
+
+type BillingActive struct {
+	BillingActive bool `json:"billing_active"`
+}
+
+// AccessLogParameters contains all the parameters necessary (including the optional ones) for a GetAccessLogs() request
+type AccessLogParameters struct {
+	Count int
+	Page  int
+}
+
+// NewAccessLogParameters provides an instance of AccessLogParameters with all the sane default values set
+func NewAccessLogParameters() AccessLogParameters {
+	return AccessLogParameters{
+		Count: DEFAULT_LOGINS_COUNT,
+		Page:  DEFAULT_LOGINS_PAGE,
+	}
+}
+
+func (api *Client) teamRequest(ctx context.Context, path string, values url.Values) (*TeamResponse, error) {
+	response := &TeamResponse{}
+	err := api.postMethod(ctx, path, values, response)
+	if err != nil {
+		return nil, err
+	}
+
+	return response, response.Err()
+}
+
+func (api *Client) billableInfoRequest(ctx context.Context, path string, values url.Values) (map[string]BillingActive, error) {
+	response := &BillableInfoResponse{}
+	err := api.postMethod(ctx, path, values, response)
+	if err != nil {
+		return nil, err
+	}
+
+	return response.BillableInfo, response.Err()
+}
+
+func (api *Client) accessLogsRequest(ctx context.Context, path string, values url.Values) (*LoginResponse, error) {
+	response := &LoginResponse{}
+	err := api.postMethod(ctx, path, values, response)
+	if err != nil {
+		return nil, err
+	}
+	return response, response.Err()
+}
+
+// GetTeamInfo gets the Team Information of the user
+func (api *Client) GetTeamInfo() (*TeamInfo, error) {
+	return api.GetTeamInfoContext(context.Background())
+}
+
+// GetTeamInfoContext gets the Team Information of the user with a custom context
+func (api *Client) GetTeamInfoContext(ctx context.Context) (*TeamInfo, error) {
+	values := url.Values{
+		"token": {api.token},
+	}
+
+	response, err := api.teamRequest(ctx, "team.info", values)
+	if err != nil {
+		return nil, err
+	}
+	return &response.Team, nil
+}
+
+// GetAccessLogs retrieves a page of logins according to the parameters given
+func (api *Client) GetAccessLogs(params AccessLogParameters) ([]Login, *Paging, error) {
+	return api.GetAccessLogsContext(context.Background(), params)
+}
+
+// GetAccessLogsContext retrieves a page of logins according to the parameters given with a custom context
+func (api *Client) GetAccessLogsContext(ctx context.Context, params AccessLogParameters) ([]Login, *Paging, error) {
+	values := url.Values{
+		"token": {api.token},
+	}
+	if params.Count != DEFAULT_LOGINS_COUNT {
+		values.Add("count", strconv.Itoa(params.Count))
+	}
+	if params.Page != DEFAULT_LOGINS_PAGE {
+		values.Add("page", strconv.Itoa(params.Page))
+	}
+
+	response, err := api.accessLogsRequest(ctx, "team.accessLogs", values)
+	if err != nil {
+		return nil, nil, err
+	}
+	return response.Logins, &response.Paging, nil
+}
+
+// GetBillableInfo ...
+func (api *Client) GetBillableInfo(user string) (map[string]BillingActive, error) {
+	return api.GetBillableInfoContext(context.Background(), user)
+}
+
+// GetBillableInfoContext ...
+func (api *Client) GetBillableInfoContext(ctx context.Context, user string) (map[string]BillingActive, error) {
+	values := url.Values{
+		"token": {api.token},
+		"user":  {user},
+	}
+
+	return api.billableInfoRequest(ctx, "team.billableInfo", values)
+}
+
+// GetBillableInfoForTeam returns the billing_active status of all users on the team.
+func (api *Client) GetBillableInfoForTeam() (map[string]BillingActive, error) {
+	return api.GetBillableInfoForTeamContext(context.Background())
+}
+
+// GetBillableInfoForTeamContext returns the billing_active status of all users on the team with a custom context
+func (api *Client) GetBillableInfoForTeamContext(ctx context.Context) (map[string]BillingActive, error) {
+	values := url.Values{
+		"token": {api.token},
+	}
+
+	return api.billableInfoRequest(ctx, "team.billableInfo", values)
+}
diff --git a/vendor/github.com/slack-go/slack/usergroups.go b/vendor/github.com/slack-go/slack/usergroups.go
new file mode 100644
index 00000000..9417f817
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/usergroups.go
@@ -0,0 +1,258 @@
+package slack
+
+import (
+	"context"
+	"net/url"
+	"strings"
+)
+
+// UserGroup contains all the information of a user group
+type UserGroup struct {
+	ID          string         `json:"id"`
+	TeamID      string         `json:"team_id"`
+	IsUserGroup bool           `json:"is_usergroup"`
+	Name        string         `json:"name"`
+	Description string         `json:"description"`
+	Handle      string         `json:"handle"`
+	IsExternal  bool           `json:"is_external"`
+	DateCreate  JSONTime       `json:"date_create"`
+	DateUpdate  JSONTime       `json:"date_update"`
+	DateDelete  JSONTime       `json:"date_delete"`
+	AutoType    string         `json:"auto_type"`
+	CreatedBy   string         `json:"created_by"`
+	UpdatedBy   string         `json:"updated_by"`
+	DeletedBy   string         `json:"deleted_by"`
+	Prefs       UserGroupPrefs `json:"prefs"`
+	UserCount   int            `json:"user_count"`
+	Users       []string       `json:"users"`
+}
+
+// UserGroupPrefs contains default channels and groups (private channels)
+type UserGroupPrefs struct {
+	Channels []string `json:"channels"`
+	Groups   []string `json:"groups"`
+}
+
+type userGroupResponseFull struct {
+	UserGroups []UserGroup `json:"usergroups"`
+	UserGroup  UserGroup   `json:"usergroup"`
+	Users      []string    `json:"users"`
+	SlackResponse
+}
+
+func (api *Client) userGroupRequest(ctx context.Context, path string, values url.Values) (*userGroupResponseFull, error) {
+	response := &userGroupResponseFull{}
+	err := api.postMethod(ctx, path, values, response)
+	if err != nil {
+		return nil, err
+	}
+
+	return response, response.Err()
+}
+
+// CreateUserGroup creates a new user group
+func (api *Client) CreateUserGroup(userGroup UserGroup) (UserGroup, error) {
+	return api.CreateUserGroupContext(context.Background(), userGroup)
+}
+
+// CreateUserGroupContext creates a new user group with a custom context
+func (api *Client) CreateUserGroupContext(ctx context.Context, userGroup UserGroup) (UserGroup, error) {
+	values := url.Values{
+		"token": {api.token},
+		"name":  {userGroup.Name},
+	}
+
+	if userGroup.Handle != "" {
+		values["handle"] = []string{userGroup.Handle}
+	}
+
+	if userGroup.Description != "" {
+		values["description"] = []string{userGroup.Description}
+	}
+
+	if len(userGroup.Prefs.Channels) > 0 {
+		values["channels"] = []string{strings.Join(userGroup.Prefs.Channels, ",")}
+	}
+
+	response, err := api.userGroupRequest(ctx, "usergroups.create", values)
+	if err != nil {
+		return UserGroup{}, err
+	}
+	return response.UserGroup, nil
+}
+
+// DisableUserGroup disables an existing user group
+func (api *Client) DisableUserGroup(userGroup string) (UserGroup, error) {
+	return api.DisableUserGroupContext(context.Background(), userGroup)
+}
+
+// DisableUserGroupContext disables an existing user group with a custom context
+func (api *Client) DisableUserGroupContext(ctx context.Context, userGroup string) (UserGroup, error) {
+	values := url.Values{
+		"token":     {api.token},
+		"usergroup": {userGroup},
+	}
+
+	response, err := api.userGroupRequest(ctx, "usergroups.disable", values)
+	if err != nil {
+		return UserGroup{}, err
+	}
+	return response.UserGroup, nil
+}
+
+// EnableUserGroup enables an existing user group
+func (api *Client) EnableUserGroup(userGroup string) (UserGroup, error) {
+	return api.EnableUserGroupContext(context.Background(), userGroup)
+}
+
+// EnableUserGroupContext enables an existing user group with a custom context
+func (api *Client) EnableUserGroupContext(ctx context.Context, userGroup string) (UserGroup, error) {
+	values := url.Values{
+		"token":     {api.token},
+		"usergroup": {userGroup},
+	}
+
+	response, err := api.userGroupRequest(ctx, "usergroups.enable", values)
+	if err != nil {
+		return UserGroup{}, err
+	}
+	return response.UserGroup, nil
+}
+
+// GetUserGroupsOption options for the GetUserGroups method call.
+type GetUserGroupsOption func(*GetUserGroupsParams)
+
+// GetUserGroupsOptionIncludeCount include the number of users in each User Group (default: false)
+func GetUserGroupsOptionIncludeCount(b bool) GetUserGroupsOption {
+	return func(params *GetUserGroupsParams) {
+		params.IncludeCount = b
+	}
+}
+
+// GetUserGroupsOptionIncludeDisabled include disabled User Groups (default: false)
+func GetUserGroupsOptionIncludeDisabled(b bool) GetUserGroupsOption {
+	return func(params *GetUserGroupsParams) {
+		params.IncludeDisabled = b
+	}
+}
+
+// GetUserGroupsOptionIncludeUsers include the list of users for each User Group (default: false)
+func GetUserGroupsOptionIncludeUsers(b bool) GetUserGroupsOption {
+	return func(params *GetUserGroupsParams) {
+		params.IncludeUsers = b
+	}
+}
+
+// GetUserGroupsParams contains arguments for GetUserGroups method call
+type GetUserGroupsParams struct {
+	IncludeCount    bool
+	IncludeDisabled bool
+	IncludeUsers    bool
+}
+
+// GetUserGroups returns a list of user groups for the team
+func (api *Client) GetUserGroups(options ...GetUserGroupsOption) ([]UserGroup, error) {
+	return api.GetUserGroupsContext(context.Background(), options...)
+}
+
+// GetUserGroupsContext returns a list of user groups for the team with a custom context
+func (api *Client) GetUserGroupsContext(ctx context.Context, options ...GetUserGroupsOption) ([]UserGroup, error) {
+	params := GetUserGroupsParams{}
+
+	for _, opt := range options {
+		opt(&params)
+	}
+
+	values := url.Values{
+		"token": {api.token},
+	}
+	if params.IncludeCount {
+		values.Add("include_count", "true")
+	}
+	if params.IncludeDisabled {
+		values.Add("include_disabled", "true")
+	}
+	if params.IncludeUsers {
+		values.Add("include_users", "true")
+	}
+
+	response, err := api.userGroupRequest(ctx, "usergroups.list", values)
+	if err != nil {
+		return nil, err
+	}
+	return response.UserGroups, nil
+}
+
+// UpdateUserGroup will update an existing user group
+func (api *Client) UpdateUserGroup(userGroup UserGroup) (UserGroup, error) {
+	return api.UpdateUserGroupContext(context.Background(), userGroup)
+}
+
+// UpdateUserGroupContext will update an existing user group with a custom context
+func (api *Client) UpdateUserGroupContext(ctx context.Context, userGroup UserGroup) (UserGroup, error) {
+	values := url.Values{
+		"token":     {api.token},
+		"usergroup": {userGroup.ID},
+	}
+
+	if userGroup.Name != "" {
+		values["name"] = []string{userGroup.Name}
+	}
+
+	if userGroup.Handle != "" {
+		values["handle"] = []string{userGroup.Handle}
+	}
+
+	if userGroup.Description != "" {
+		values["description"] = []string{userGroup.Description}
+	}
+
+	if len(userGroup.Prefs.Channels) > 0 {
+		values["channels"] = []string{strings.Join(userGroup.Prefs.Channels, ",")}
+	}
+
+	response, err := api.userGroupRequest(ctx, "usergroups.update", values)
+	if err != nil {
+		return UserGroup{}, err
+	}
+	return response.UserGroup, nil
+}
+
+// GetUserGroupMembers will retrieve the current list of users in a group
+func (api *Client) GetUserGroupMembers(userGroup string) ([]string, error) {
+	return api.GetUserGroupMembersContext(context.Background(), userGroup)
+}
+
+// GetUserGroupMembersContext will retrieve the current list of users in a group with a custom context
+func (api *Client) GetUserGroupMembersContext(ctx context.Context, userGroup string) ([]string, error) {
+	values := url.Values{
+		"token":     {api.token},
+		"usergroup": {userGroup},
+	}
+
+	response, err := api.userGroupRequest(ctx, "usergroups.users.list", values)
+	if err != nil {
+		return []string{}, err
+	}
+	return response.Users, nil
+}
+
+// UpdateUserGroupMembers will update the members of an existing user group
+func (api *Client) UpdateUserGroupMembers(userGroup string, members string) (UserGroup, error) {
+	return api.UpdateUserGroupMembersContext(context.Background(), userGroup, members)
+}
+
+// UpdateUserGroupMembersContext will update the members of an existing user group with a custom context
+func (api *Client) UpdateUserGroupMembersContext(ctx context.Context, userGroup string, members string) (UserGroup, error) {
+	values := url.Values{
+		"token":     {api.token},
+		"usergroup": {userGroup},
+		"users":     {members},
+	}
+
+	response, err := api.userGroupRequest(ctx, "usergroups.users.update", values)
+	if err != nil {
+		return UserGroup{}, err
+	}
+	return response.UserGroup, nil
+}
diff --git a/vendor/github.com/slack-go/slack/users.go b/vendor/github.com/slack-go/slack/users.go
new file mode 100644
index 00000000..6001e0fa
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/users.go
@@ -0,0 +1,597 @@
+package slack
+
+import (
+	"context"
+	"encoding/json"
+	"net/url"
+	"strconv"
+	"time"
+)
+
+const (
+	DEFAULT_USER_PHOTO_CROP_X = -1
+	DEFAULT_USER_PHOTO_CROP_Y = -1
+	DEFAULT_USER_PHOTO_CROP_W = -1
+)
+
+// UserProfile contains all the information details of a given user
+type UserProfile struct {
+	FirstName             string                  `json:"first_name"`
+	LastName              string                  `json:"last_name"`
+	RealName              string                  `json:"real_name"`
+	RealNameNormalized    string                  `json:"real_name_normalized"`
+	DisplayName           string                  `json:"display_name"`
+	DisplayNameNormalized string                  `json:"display_name_normalized"`
+	Email                 string                  `json:"email"`
+	Skype                 string                  `json:"skype"`
+	Phone                 string                  `json:"phone"`
+	Image24               string                  `json:"image_24"`
+	Image32               string                  `json:"image_32"`
+	Image48               string                  `json:"image_48"`
+	Image72               string                  `json:"image_72"`
+	Image192              string                  `json:"image_192"`
+	ImageOriginal         string                  `json:"image_original"`
+	Title                 string                  `json:"title"`
+	BotID                 string                  `json:"bot_id,omitempty"`
+	ApiAppID              string                  `json:"api_app_id,omitempty"`
+	StatusText            string                  `json:"status_text,omitempty"`
+	StatusEmoji           string                  `json:"status_emoji,omitempty"`
+	StatusExpiration      int                     `json:"status_expiration"`
+	Team                  string                  `json:"team"`
+	Fields                UserProfileCustomFields `json:"fields"`
+}
+
+// UserProfileCustomFields represents user profile's custom fields.
+// Slack API's response data type is inconsistent so we use the struct.
+// For detail, please see below.
+// https://github.com/slack-go/slack/pull/298#discussion_r185159233
+type UserProfileCustomFields struct {
+	fields map[string]UserProfileCustomField
+}
+
+// UnmarshalJSON is the implementation of the json.Unmarshaler interface.
+func (fields *UserProfileCustomFields) UnmarshalJSON(b []byte) error {
+	// https://github.com/slack-go/slack/pull/298#discussion_r185159233
+	if string(b) == "[]" {
+		return nil
+	}
+	return json.Unmarshal(b, &fields.fields)
+}
+
+// MarshalJSON is the implementation of the json.Marshaler interface.
+func (fields UserProfileCustomFields) MarshalJSON() ([]byte, error) {
+	if len(fields.fields) == 0 {
+		return []byte("[]"), nil
+	}
+	return json.Marshal(fields.fields)
+}
+
+// ToMap returns a map of custom fields.
+func (fields *UserProfileCustomFields) ToMap() map[string]UserProfileCustomField {
+	return fields.fields
+}
+
+// Len returns the number of custom fields.
+func (fields *UserProfileCustomFields) Len() int {
+	return len(fields.fields)
+}
+
+// SetMap sets a map of custom fields.
+func (fields *UserProfileCustomFields) SetMap(m map[string]UserProfileCustomField) {
+	fields.fields = m
+}
+
+// FieldsMap returns a map of custom fields.
+func (profile *UserProfile) FieldsMap() map[string]UserProfileCustomField {
+	return profile.Fields.ToMap()
+}
+
+// SetFieldsMap sets a map of custom fields.
+func (profile *UserProfile) SetFieldsMap(m map[string]UserProfileCustomField) {
+	profile.Fields.SetMap(m)
+}
+
+// UserProfileCustomField represents a custom user profile field
+type UserProfileCustomField struct {
+	Value string `json:"value"`
+	Alt   string `json:"alt"`
+	Label string `json:"label"`
+}
+
+// User contains all the information of a user
+type User struct {
+	ID                string         `json:"id"`
+	TeamID            string         `json:"team_id"`
+	Name              string         `json:"name"`
+	Deleted           bool           `json:"deleted"`
+	Color             string         `json:"color"`
+	RealName          string         `json:"real_name"`
+	TZ                string         `json:"tz,omitempty"`
+	TZLabel           string         `json:"tz_label"`
+	TZOffset          int            `json:"tz_offset"`
+	Profile           UserProfile    `json:"profile"`
+	IsBot             bool           `json:"is_bot"`
+	IsAdmin           bool           `json:"is_admin"`
+	IsOwner           bool           `json:"is_owner"`
+	IsPrimaryOwner    bool           `json:"is_primary_owner"`
+	IsRestricted      bool           `json:"is_restricted"`
+	IsUltraRestricted bool           `json:"is_ultra_restricted"`
+	IsStranger        bool           `json:"is_stranger"`
+	IsAppUser         bool           `json:"is_app_user"`
+	IsInvitedUser     bool           `json:"is_invited_user"`
+	Has2FA            bool           `json:"has_2fa"`
+	HasFiles          bool           `json:"has_files"`
+	Presence          string         `json:"presence"`
+	Locale            string         `json:"locale"`
+	Updated           JSONTime       `json:"updated"`
+	Enterprise        EnterpriseUser `json:"enterprise_user,omitempty"`
+}
+
+// UserPresence contains details about a user online status
+type UserPresence struct {
+	Presence        string   `json:"presence,omitempty"`
+	Online          bool     `json:"online,omitempty"`
+	AutoAway        bool     `json:"auto_away,omitempty"`
+	ManualAway      bool     `json:"manual_away,omitempty"`
+	ConnectionCount int      `json:"connection_count,omitempty"`
+	LastActivity    JSONTime `json:"last_activity,omitempty"`
+}
+
+type UserIdentityResponse struct {
+	User UserIdentity `json:"user"`
+	Team TeamIdentity `json:"team"`
+	SlackResponse
+}
+
+type UserIdentity struct {
+	ID       string `json:"id"`
+	Name     string `json:"name"`
+	Email    string `json:"email"`
+	Image24  string `json:"image_24"`
+	Image32  string `json:"image_32"`
+	Image48  string `json:"image_48"`
+	Image72  string `json:"image_72"`
+	Image192 string `json:"image_192"`
+	Image512 string `json:"image_512"`
+}
+
+// EnterpriseUser is present when a user is part of Slack Enterprise Grid
+// https://api.slack.com/types/user#enterprise_grid_user_objects
+type EnterpriseUser struct {
+	ID             string   `json:"id"`
+	EnterpriseID   string   `json:"enterprise_id"`
+	EnterpriseName string   `json:"enterprise_name"`
+	IsAdmin        bool     `json:"is_admin"`
+	IsOwner        bool     `json:"is_owner"`
+	Teams          []string `json:"teams"`
+}
+
+type TeamIdentity struct {
+	ID            string `json:"id"`
+	Name          string `json:"name"`
+	Domain        string `json:"domain"`
+	Image34       string `json:"image_34"`
+	Image44       string `json:"image_44"`
+	Image68       string `json:"image_68"`
+	Image88       string `json:"image_88"`
+	Image102      string `json:"image_102"`
+	Image132      string `json:"image_132"`
+	Image230      string `json:"image_230"`
+	ImageDefault  bool   `json:"image_default"`
+	ImageOriginal string `json:"image_original"`
+}
+
+type userResponseFull struct {
+	Members []User `json:"members,omitempty"`
+	User    `json:"user,omitempty"`
+	UserPresence
+	SlackResponse
+	Metadata ResponseMetadata `json:"response_metadata"`
+}
+
+type UserSetPhotoParams struct {
+	CropX int
+	CropY int
+	CropW int
+}
+
+func NewUserSetPhotoParams() UserSetPhotoParams {
+	return UserSetPhotoParams{
+		CropX: DEFAULT_USER_PHOTO_CROP_X,
+		CropY: DEFAULT_USER_PHOTO_CROP_Y,
+		CropW: DEFAULT_USER_PHOTO_CROP_W,
+	}
+}
+
+func (api *Client) userRequest(ctx context.Context, path string, values url.Values) (*userResponseFull, error) {
+	response := &userResponseFull{}
+	err := api.postMethod(ctx, path, values, response)
+	if err != nil {
+		return nil, err
+	}
+
+	return response, response.Err()
+}
+
+// GetUserPresence will retrieve the current presence status of given user.
+func (api *Client) GetUserPresence(user string) (*UserPresence, error) {
+	return api.GetUserPresenceContext(context.Background(), user)
+}
+
+// GetUserPresenceContext will retrieve the current presence status of given user with a custom context.
+func (api *Client) GetUserPresenceContext(ctx context.Context, user string) (*UserPresence, error) {
+	values := url.Values{
+		"token": {api.token},
+		"user":  {user},
+	}
+
+	response, err := api.userRequest(ctx, "users.getPresence", values)
+	if err != nil {
+		return nil, err
+	}
+	return &response.UserPresence, nil
+}
+
+// GetUserInfo will retrieve the complete user information
+func (api *Client) GetUserInfo(user string) (*User, error) {
+	return api.GetUserInfoContext(context.Background(), user)
+}
+
+// GetUserInfoContext will retrieve the complete user information with a custom context
+func (api *Client) GetUserInfoContext(ctx context.Context, user string) (*User, error) {
+	values := url.Values{
+		"token":          {api.token},
+		"user":           {user},
+		"include_locale": {strconv.FormatBool(true)},
+	}
+
+	response, err := api.userRequest(ctx, "users.info", values)
+	if err != nil {
+		return nil, err
+	}
+	return &response.User, nil
+}
+
+// GetUsersOption options for the GetUsers method call.
+type GetUsersOption func(*UserPagination)
+
+// GetUsersOptionLimit limit the number of users returned
+func GetUsersOptionLimit(n int) GetUsersOption {
+	return func(p *UserPagination) {
+		p.limit = n
+	}
+}
+
+// GetUsersOptionPresence include user presence
+func GetUsersOptionPresence(n bool) GetUsersOption {
+	return func(p *UserPagination) {
+		p.presence = n
+	}
+}
+
+func newUserPagination(c *Client, options ...GetUsersOption) (up UserPagination) {
+	up = UserPagination{
+		c:     c,
+		limit: 200, // per slack api documentation.
+	}
+
+	for _, opt := range options {
+		opt(&up)
+	}
+
+	return up
+}
+
+// UserPagination allows for paginating over the users
+type UserPagination struct {
+	Users        []User
+	limit        int
+	presence     bool
+	previousResp *ResponseMetadata
+	c            *Client
+}
+
+// Done checks if the pagination has completed
+func (UserPagination) Done(err error) bool {
+	return err == errPaginationComplete
+}
+
+// Failure checks if pagination failed.
+func (t UserPagination) Failure(err error) error {
+	if t.Done(err) {
+		return nil
+	}
+
+	return err
+}
+
+func (t UserPagination) Next(ctx context.Context) (_ UserPagination, err error) {
+	var (
+		resp *userResponseFull
+	)
+
+	if t.c == nil || (t.previousResp != nil && t.previousResp.Cursor == "") {
+		return t, errPaginationComplete
+	}
+
+	t.previousResp = t.previousResp.initialize()
+
+	values := url.Values{
+		"limit":          {strconv.Itoa(t.limit)},
+		"presence":       {strconv.FormatBool(t.presence)},
+		"token":          {t.c.token},
+		"cursor":         {t.previousResp.Cursor},
+		"include_locale": {strconv.FormatBool(true)},
+	}
+
+	if resp, err = t.c.userRequest(ctx, "users.list", values); err != nil {
+		return t, err
+	}
+
+	t.c.Debugf("GetUsersContext: got %d users; metadata %v", len(resp.Members), resp.Metadata)
+	t.Users = resp.Members
+	t.previousResp = &resp.Metadata
+
+	return t, nil
+}
+
+// GetUsersPaginated fetches users in a paginated fashion, see GetUsersContext for usage.
+func (api *Client) GetUsersPaginated(options ...GetUsersOption) UserPagination {
+	return newUserPagination(api, options...)
+}
+
+// GetUsers returns the list of users (with their detailed information)
+func (api *Client) GetUsers() ([]User, error) {
+	return api.GetUsersContext(context.Background())
+}
+
+// GetUsersContext returns the list of users (with their detailed information) with a custom context
+func (api *Client) GetUsersContext(ctx context.Context) (results []User, err error) {
+	p := api.GetUsersPaginated()
+	for err == nil {
+		p, err = p.Next(ctx)
+		if err == nil {
+			results = append(results, p.Users...)
+		} else if rateLimitedError, ok := err.(*RateLimitedError); ok {
+			select {
+			case <-ctx.Done():
+				err = ctx.Err()
+			case <-time.After(rateLimitedError.RetryAfter):
+				err = nil
+			}
+		}
+	}
+
+	return results, p.Failure(err)
+}
+
+// GetUserByEmail will retrieve the complete user information by email
+func (api *Client) GetUserByEmail(email string) (*User, error) {
+	return api.GetUserByEmailContext(context.Background(), email)
+}
+
+// GetUserByEmailContext will retrieve the complete user information by email with a custom context
+func (api *Client) GetUserByEmailContext(ctx context.Context, email string) (*User, error) {
+	values := url.Values{
+		"token": {api.token},
+		"email": {email},
+	}
+	response, err := api.userRequest(ctx, "users.lookupByEmail", values)
+	if err != nil {
+		return nil, err
+	}
+	return &response.User, nil
+}
+
+// SetUserAsActive marks the currently authenticated user as active
+func (api *Client) SetUserAsActive() error {
+	return api.SetUserAsActiveContext(context.Background())
+}
+
+// SetUserAsActiveContext marks the currently authenticated user as active with a custom context
+func (api *Client) SetUserAsActiveContext(ctx context.Context) (err error) {
+	values := url.Values{
+		"token": {api.token},
+	}
+
+	_, err = api.userRequest(ctx, "users.setActive", values)
+	return err
+}
+
+// SetUserPresence changes the currently authenticated user presence
+func (api *Client) SetUserPresence(presence string) error {
+	return api.SetUserPresenceContext(context.Background(), presence)
+}
+
+// SetUserPresenceContext changes the currently authenticated user presence with a custom context
+func (api *Client) SetUserPresenceContext(ctx context.Context, presence string) error {
+	values := url.Values{
+		"token":    {api.token},
+		"presence": {presence},
+	}
+
+	_, err := api.userRequest(ctx, "users.setPresence", values)
+	return err
+}
+
+// GetUserIdentity will retrieve user info available per identity scopes
+func (api *Client) GetUserIdentity() (*UserIdentityResponse, error) {
+	return api.GetUserIdentityContext(context.Background())
+}
+
+// GetUserIdentityContext will retrieve user info available per identity scopes with a custom context
+func (api *Client) GetUserIdentityContext(ctx context.Context) (response *UserIdentityResponse, err error) {
+	values := url.Values{
+		"token": {api.token},
+	}
+	response = &UserIdentityResponse{}
+
+	err = api.postMethod(ctx, "users.identity", values, response)
+	if err != nil {
+		return nil, err
+	}
+
+	if err := response.Err(); err != nil {
+		return nil, err
+	}
+
+	return response, nil
+}
+
+// SetUserPhoto changes the currently authenticated user's profile image
+func (api *Client) SetUserPhoto(image string, params UserSetPhotoParams) error {
+	return api.SetUserPhotoContext(context.Background(), image, params)
+}
+
+// SetUserPhotoContext changes the currently authenticated user's profile image using a custom context
+func (api *Client) SetUserPhotoContext(ctx context.Context, image string, params UserSetPhotoParams) (err error) {
+	response := &SlackResponse{}
+	values := url.Values{
+		"token": {api.token},
+	}
+	if params.CropX != DEFAULT_USER_PHOTO_CROP_X {
+		values.Add("crop_x", strconv.Itoa(params.CropX))
+	}
+	if params.CropY != DEFAULT_USER_PHOTO_CROP_Y {
+		values.Add("crop_y", strconv.Itoa(params.CropX))
+	}
+	if params.CropW != DEFAULT_USER_PHOTO_CROP_W {
+		values.Add("crop_w", strconv.Itoa(params.CropW))
+	}
+
+	err = postLocalWithMultipartResponse(ctx, api.httpclient, api.endpoint+"users.setPhoto", image, "image", values, response, api)
+	if err != nil {
+		return err
+	}
+
+	return response.Err()
+}
+
+// DeleteUserPhoto deletes the current authenticated user's profile image
+func (api *Client) DeleteUserPhoto() error {
+	return api.DeleteUserPhotoContext(context.Background())
+}
+
+// DeleteUserPhotoContext deletes the current authenticated user's profile image with a custom context
+func (api *Client) DeleteUserPhotoContext(ctx context.Context) (err error) {
+	response := &SlackResponse{}
+	values := url.Values{
+		"token": {api.token},
+	}
+
+	err = api.postMethod(ctx, "users.deletePhoto", values, response)
+	if err != nil {
+		return err
+	}
+
+	return response.Err()
+}
+
+// SetUserCustomStatus will set a custom status and emoji for the currently
+// authenticated user. If statusEmoji is "" and statusText is not, the Slack API
+// will automatically set it to ":speech_balloon:". Otherwise, if both are ""
+// the Slack API will unset the custom status/emoji. If statusExpiration is set to 0
+// the status will not expire.
+func (api *Client) SetUserCustomStatus(statusText, statusEmoji string, statusExpiration int64) error {
+	return api.SetUserCustomStatusContextWithUser(context.Background(), "", statusText, statusEmoji, statusExpiration)
+}
+
+// SetUserCustomStatusContext will set a custom status and emoji for the currently authenticated user with a custom context
+//
+// For more information see SetUserCustomStatus
+func (api *Client) SetUserCustomStatusContext(ctx context.Context, statusText, statusEmoji string, statusExpiration int64) error {
+	return api.SetUserCustomStatusContextWithUser(context.Background(), "", statusText, statusEmoji, statusExpiration)
+}
+
+// SetUserCustomStatusWithUser will set a custom status and emoji for the provided user.
+//
+// For more information see SetUserCustomStatus
+func (api *Client) SetUserCustomStatusWithUser(user, statusText, statusEmoji string, statusExpiration int64) error {
+	return api.SetUserCustomStatusContextWithUser(context.Background(), user, statusText, statusEmoji, statusExpiration)
+}
+
+// SetUserCustomStatusContextWithUser will set a custom status and emoji for the provided user with a custom context
+//
+// For more information see SetUserCustomStatus
+func (api *Client) SetUserCustomStatusContextWithUser(ctx context.Context, user, statusText, statusEmoji string, statusExpiration int64) error {
+	// XXX(theckman): this anonymous struct is for making requests to the Slack
+	// API for setting and unsetting a User's Custom Status/Emoji. To change
+	// these values we must provide a JSON document as the profile POST field.
+	//
+	// We use an anonymous struct over UserProfile because to unset the values
+	// on the User's profile we cannot use the `json:"omitempty"` tag. This is
+	// because an empty string ("") is what's used to unset the values. Check
+	// out the API docs for more details:
+	//
+	// - https://api.slack.com/docs/presence-and-status#custom_status
+	profile, err := json.Marshal(
+		&struct {
+			StatusText       string `json:"status_text"`
+			StatusEmoji      string `json:"status_emoji"`
+			StatusExpiration int64  `json:"status_expiration"`
+		}{
+			StatusText:       statusText,
+			StatusEmoji:      statusEmoji,
+			StatusExpiration: statusExpiration,
+		},
+	)
+
+	if err != nil {
+		return err
+	}
+
+	values := url.Values{
+		"user":    {user},
+		"token":   {api.token},
+		"profile": {string(profile)},
+	}
+
+	response := &userResponseFull{}
+	if err = api.postMethod(ctx, "users.profile.set", values, response); err != nil {
+		return err
+	}
+
+	return response.Err()
+}
+
+// UnsetUserCustomStatus removes the custom status message for the currently
+// authenticated user. This is a convenience method that wraps (*Client).SetUserCustomStatus().
+func (api *Client) UnsetUserCustomStatus() error {
+	return api.UnsetUserCustomStatusContext(context.Background())
+}
+
+// UnsetUserCustomStatusContext removes the custom status message for the currently authenticated user
+// with a custom context. This is a convenience method that wraps (*Client).SetUserCustomStatus().
+func (api *Client) UnsetUserCustomStatusContext(ctx context.Context) error {
+	return api.SetUserCustomStatusContext(ctx, "", "", 0)
+}
+
+// GetUserProfile retrieves a user's profile information.
+func (api *Client) GetUserProfile(userID string, includeLabels bool) (*UserProfile, error) {
+	return api.GetUserProfileContext(context.Background(), userID, includeLabels)
+}
+
+type getUserProfileResponse struct {
+	SlackResponse
+	Profile *UserProfile `json:"profile"`
+}
+
+// GetUserProfileContext retrieves a user's profile information with a context.
+func (api *Client) GetUserProfileContext(ctx context.Context, userID string, includeLabels bool) (*UserProfile, error) {
+	values := url.Values{"token": {api.token}, "user": {userID}}
+	if includeLabels {
+		values.Add("include_labels", "true")
+	}
+	resp := &getUserProfileResponse{}
+
+	err := api.postMethod(ctx, "users.profile.get", values, &resp)
+	if err != nil {
+		return nil, err
+	}
+
+	if err := resp.Err(); err != nil {
+		return nil, err
+	}
+
+	return resp.Profile, nil
+}
diff --git a/vendor/github.com/slack-go/slack/views.go b/vendor/github.com/slack-go/slack/views.go
new file mode 100644
index 00000000..afe391bf
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/views.go
@@ -0,0 +1,221 @@
+package slack
+
+import (
+	"context"
+	"encoding/json"
+)
+
+const (
+	VTModal   ViewType = "modal"
+	VTHomeTab ViewType = "home"
+)
+
+type ViewType string
+
+type View struct {
+	SlackResponse
+	ID              string           `json:"id"`
+	TeamID          string           `json:"team_id"`
+	Type            ViewType         `json:"type"`
+	Title           *TextBlockObject `json:"title"`
+	Close           *TextBlockObject `json:"close"`
+	Submit          *TextBlockObject `json:"submit"`
+	Blocks          Blocks           `json:"blocks"`
+	PrivateMetadata string           `json:"private_metadata"`
+	CallbackID      string           `json:"callback_id"`
+	State           interface{}      `json:"state"`
+	Hash            string           `json:"hash"`
+	ClearOnClose    bool             `json:"clear_on_close"`
+	NotifyOnClose   bool             `json:"notify_on_close"`
+	RootViewID      string           `json:"root_view_id"`
+	PreviousViewID  string           `json:"previous_view_id"`
+	AppID           string           `json:"app_id"`
+	ExternalID      string           `json:"external_id"`
+	BotID           string           `json:"bot_id"`
+}
+
+type ModalViewRequest struct {
+	Type            ViewType         `json:"type"`
+	Title           *TextBlockObject `json:"title"`
+	Blocks          Blocks           `json:"blocks"`
+	Close           *TextBlockObject `json:"close"`
+	Submit          *TextBlockObject `json:"submit"`
+	PrivateMetadata string           `json:"private_metadata"`
+	CallbackID      string           `json:"callback_id"`
+	ClearOnClose    bool             `json:"clear_on_close"`
+	NotifyOnClose   bool             `json:"notify_on_close"`
+	ExternalID      string           `json:"external_id"`
+}
+
+func (v *ModalViewRequest) ViewType() ViewType {
+	return v.Type
+}
+
+type HomeTabViewRequest struct {
+	Type            ViewType `json:"type"`
+	Blocks          Blocks   `json:"blocks"`
+	PrivateMetadata string   `json:"private_metadata"`
+	CallbackID      string   `json:"callback_id"`
+	ExternalID      string   `json:"external_id"`
+}
+
+func (v *HomeTabViewRequest) ViewType() ViewType {
+	return v.Type
+}
+
+type openViewRequest struct {
+	TriggerID string           `json:"trigger_id"`
+	View      ModalViewRequest `json:"view"`
+}
+
+type publishViewRequest struct {
+	UserID string             `json:"user_id"`
+	View   HomeTabViewRequest `json:"view"`
+	Hash   string             `json:"hash"`
+}
+
+type pushViewRequest struct {
+	TriggerID string           `json:"trigger_id"`
+	View      ModalViewRequest `json:"view"`
+}
+
+type updateViewRequest struct {
+	View       ModalViewRequest `json:"view"`
+	ExternalID string           `json:"external_id"`
+	Hash       string           `json:"hash"`
+	ViewID     string           `json:"view_id"`
+}
+
+type ViewResponse struct {
+	SlackResponse
+	View `json:"view"`
+}
+
+// OpenView opens a view for a user.
+func (api *Client) OpenView(triggerID string, view ModalViewRequest) (*ViewResponse, error) {
+	return api.OpenViewContext(context.Background(), triggerID, view)
+}
+
+// OpenViewContext opens a view for a user with a custom context.
+func (api *Client) OpenViewContext(
+	ctx context.Context,
+	triggerID string,
+	view ModalViewRequest,
+) (*ViewResponse, error) {
+	if triggerID == "" {
+		return nil, ErrParametersMissing
+	}
+	req := openViewRequest{
+		TriggerID: triggerID,
+		View:      view,
+	}
+	encoded, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	endpoint := api.endpoint + "views.open"
+	resp := &ViewResponse{}
+	err = postJSON(ctx, api.httpclient, endpoint, api.token, encoded, resp, api)
+	if err != nil {
+		return nil, err
+	}
+	return resp, resp.Err()
+}
+
+// PublishView publishes a static view for a user.
+func (api *Client) PublishView(userID string, view HomeTabViewRequest, hash string) (*ViewResponse, error) {
+	return api.PublishViewContext(context.Background(), userID, view, hash)
+}
+
+// PublishViewContext publishes a static view for a user with a custom context.
+func (api *Client) PublishViewContext(
+	ctx context.Context,
+	userID string,
+	view HomeTabViewRequest,
+	hash string,
+) (*ViewResponse, error) {
+	if userID == "" {
+		return nil, ErrParametersMissing
+	}
+	req := publishViewRequest{
+		UserID: userID,
+		View:   view,
+		Hash:   hash,
+	}
+	encoded, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	endpoint := api.endpoint + "views.publish"
+	resp := &ViewResponse{}
+	err = postJSON(ctx, api.httpclient, endpoint, api.token, encoded, resp, api)
+	if err != nil {
+		return nil, err
+	}
+	return resp, resp.Err()
+}
+
+// PushView pushes a view onto the stack of a root view.
+func (api *Client) PushView(triggerID string, view ModalViewRequest) (*ViewResponse, error) {
+	return api.PushViewContext(context.Background(), triggerID, view)
+}
+
+// PublishViewContext pushes a view onto the stack of a root view with a custom context.
+func (api *Client) PushViewContext(
+	ctx context.Context,
+	triggerID string,
+	view ModalViewRequest,
+) (*ViewResponse, error) {
+	if triggerID == "" {
+		return nil, ErrParametersMissing
+	}
+	req := pushViewRequest{
+		TriggerID: triggerID,
+		View:      view,
+	}
+	encoded, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	endpoint := api.endpoint + "views.push"
+	resp := &ViewResponse{}
+	err = postJSON(ctx, api.httpclient, endpoint, api.token, encoded, resp, api)
+	if err != nil {
+		return nil, err
+	}
+	return resp, resp.Err()
+}
+
+// UpdateView updates an existing view.
+func (api *Client) UpdateView(view ModalViewRequest, externalID, hash, viewID string) (*ViewResponse, error) {
+	return api.UpdateViewContext(context.Background(), view, externalID, hash, viewID)
+}
+
+// UpdateViewContext updates an existing view with a custom context.
+func (api *Client) UpdateViewContext(
+	ctx context.Context,
+	view ModalViewRequest,
+	externalID, hash,
+	viewID string,
+) (*ViewResponse, error) {
+	if externalID == "" && viewID == "" {
+		return nil, ErrParametersMissing
+	}
+	req := updateViewRequest{
+		View:       view,
+		ExternalID: externalID,
+		Hash:       hash,
+		ViewID:     viewID,
+	}
+	encoded, err := json.Marshal(req)
+	if err != nil {
+		return nil, err
+	}
+	endpoint := api.endpoint + "views.update"
+	resp := &ViewResponse{}
+	err = postJSON(ctx, api.httpclient, endpoint, api.token, encoded, resp, api)
+	if err != nil {
+		return nil, err
+	}
+	return resp, resp.Err()
+}
diff --git a/vendor/github.com/slack-go/slack/webhooks.go b/vendor/github.com/slack-go/slack/webhooks.go
new file mode 100644
index 00000000..1016cb4f
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/webhooks.go
@@ -0,0 +1,29 @@
+package slack
+
+import (
+	"context"
+	"net/http"
+)
+
+type WebhookMessage struct {
+	Username        string       `json:"username,omitempty"`
+	IconEmoji       string       `json:"icon_emoji,omitempty"`
+	IconURL         string       `json:"icon_url,omitempty"`
+	Channel         string       `json:"channel,omitempty"`
+	ThreadTimestamp string       `json:"thread_ts,omitempty"`
+	Text            string       `json:"text,omitempty"`
+	Attachments     []Attachment `json:"attachments,omitempty"`
+	Parse           string       `json:"parse,omitempty"`
+}
+
+func PostWebhook(url string, msg *WebhookMessage) error {
+	return PostWebhookCustomHTTPContext(context.Background(), url, http.DefaultClient, msg)
+}
+
+func PostWebhookContext(ctx context.Context, url string, msg *WebhookMessage) error {
+	return PostWebhookCustomHTTPContext(ctx, url, http.DefaultClient, msg)
+}
+
+func PostWebhookCustomHTTP(url string, httpClient *http.Client, msg *WebhookMessage) error {
+	return PostWebhookCustomHTTPContext(context.Background(), url, httpClient, msg)
+}
diff --git a/vendor/github.com/slack-go/slack/webhooks_go112.go b/vendor/github.com/slack-go/slack/webhooks_go112.go
new file mode 100644
index 00000000..4e0db0e4
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/webhooks_go112.go
@@ -0,0 +1,34 @@
+// +build !go1.13
+
+package slack
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"net/http"
+
+	"github.com/pkg/errors"
+)
+
+func PostWebhookCustomHTTPContext(ctx context.Context, url string, httpClient *http.Client, msg *WebhookMessage) error {
+	raw, err := json.Marshal(msg)
+	if err != nil {
+		return errors.Wrap(err, "marshal failed")
+	}
+
+	req, err := http.NewRequest(http.MethodPost, url, bytes.NewReader(raw))
+	if err != nil {
+		return errors.Wrap(err, "failed new request")
+	}
+	req = req.WithContext(ctx)
+	req.Header.Set("Content-Type", "application/json")
+
+	resp, err := httpClient.Do(req)
+	if err != nil {
+		return errors.Wrap(err, "failed to post webhook")
+	}
+	defer resp.Body.Close()
+
+	return checkStatusCode(resp, discard{})
+}
diff --git a/vendor/github.com/slack-go/slack/webhooks_go113.go b/vendor/github.com/slack-go/slack/webhooks_go113.go
new file mode 100644
index 00000000..99c243f5
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/webhooks_go113.go
@@ -0,0 +1,33 @@
+// +build go1.13
+
+package slack
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"net/http"
+
+	"github.com/pkg/errors"
+)
+
+func PostWebhookCustomHTTPContext(ctx context.Context, url string, httpClient *http.Client, msg *WebhookMessage) error {
+	raw, err := json.Marshal(msg)
+	if err != nil {
+		return errors.Wrap(err, "marshal failed")
+	}
+
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, url, bytes.NewReader(raw))
+	if err != nil {
+		return errors.Wrap(err, "failed new request")
+	}
+	req.Header.Set("Content-Type", "application/json")
+
+	resp, err := httpClient.Do(req)
+	if err != nil {
+		return errors.Wrap(err, "failed to post webhook")
+	}
+	defer resp.Body.Close()
+
+	return checkStatusCode(resp, discard{})
+}
diff --git a/vendor/github.com/slack-go/slack/websocket.go b/vendor/github.com/slack-go/slack/websocket.go
new file mode 100644
index 00000000..d6895f2a
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/websocket.go
@@ -0,0 +1,103 @@
+package slack
+
+import (
+	"net/url"
+	"sync"
+	"time"
+
+	"github.com/gorilla/websocket"
+)
+
+const (
+	// MaxMessageTextLength is the current maximum message length in number of characters as defined here
+	// https://api.slack.com/rtm#limits
+	MaxMessageTextLength = 4000
+)
+
+// RTM represents a managed websocket connection. It also supports
+// all the methods of the `Client` type.
+//
+// Create this element with Client's NewRTM() or NewRTMWithOptions(*RTMOptions)
+type RTM struct {
+	// Client is the main API, embedded
+	Client
+
+	idGen        IDGenerator
+	pingInterval time.Duration
+	pingDeadman  *time.Timer
+
+	// Connection life-cycle
+	conn             *websocket.Conn
+	IncomingEvents   chan RTMEvent
+	outgoingMessages chan OutgoingMessage
+	killChannel      chan bool
+	disconnected     chan struct{}
+	disconnectedm    *sync.Once
+	forcePing        chan bool
+
+	// UserDetails upon connection
+	info *Info
+
+	// useRTMStart should be set to true if you want to use
+	// rtm.start to connect to Slack, otherwise it will use
+	// rtm.connect
+	useRTMStart bool
+
+	// dialer is a gorilla/websocket Dialer. If nil, use the default
+	// Dialer.
+	dialer *websocket.Dialer
+
+	// mu is mutex used to prevent RTM connection race conditions
+	mu *sync.Mutex
+
+	// connParams is a map of flags for connection parameters.
+	connParams url.Values
+}
+
+// signal that we are disconnected by closing the channel.
+// protect it with a mutex to ensure it only happens once.
+func (rtm *RTM) disconnect() {
+	rtm.disconnectedm.Do(func() {
+		close(rtm.disconnected)
+	})
+}
+
+// Disconnect and wait, blocking until a successful disconnection.
+func (rtm *RTM) Disconnect() error {
+	// always push into the kill channel when invoked,
+	// this lets the ManagedConnection() function properly clean up.
+	// if the buffer is full then just continue on.
+	select {
+	case rtm.killChannel <- true:
+		return nil
+	case <-rtm.disconnected:
+		return ErrAlreadyDisconnected
+	}
+}
+
+// GetInfo returns the info structure received when calling
+// "startrtm", holding metadata needed to implement a full
+// chat client. It will be non-nil after a call to StartRTM().
+func (rtm *RTM) GetInfo() *Info {
+	return rtm.info
+}
+
+// SendMessage submits a simple message through the websocket.  For
+// more complicated messages, use `rtm.PostMessage` with a complete
+// struct describing your attachments and all.
+func (rtm *RTM) SendMessage(msg *OutgoingMessage) {
+	if msg == nil {
+		rtm.Debugln("Error: Attempted to SendMessage(nil)")
+		return
+	}
+
+	rtm.outgoingMessages <- *msg
+}
+
+func (rtm *RTM) resetDeadman() {
+	rtm.pingDeadman.Reset(deadmanDuration(rtm.pingInterval))
+}
+
+func deadmanDuration(d time.Duration) time.Duration {
+	return d * 4
+}
diff --git a/vendor/github.com/slack-go/slack/websocket_channels.go b/vendor/github.com/slack-go/slack/websocket_channels.go
new file mode 100644
index 00000000..7dd3319b
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/websocket_channels.go
@@ -0,0 +1,72 @@
+package slack
+
+// ChannelCreatedEvent represents the Channel created event
+type ChannelCreatedEvent struct {
+	Type           string             `json:"type"`
+	Channel        ChannelCreatedInfo `json:"channel"`
+	EventTimestamp string             `json:"event_ts"`
+}
+
+// ChannelCreatedInfo represents the information associated with the Channel created event
+type ChannelCreatedInfo struct {
+	ID        string `json:"id"`
+	IsChannel bool   `json:"is_channel"`
+	Name      string `json:"name"`
+	Created   int    `json:"created"`
+	Creator   string `json:"creator"`
+}
+
+// ChannelJoinedEvent represents the Channel joined event
+type ChannelJoinedEvent struct {
+	Type    string  `json:"type"`
+	Channel Channel `json:"channel"`
+}
+
+// ChannelInfoEvent represents the Channel info event
+type ChannelInfoEvent struct {
+	// channel_left
+	// channel_deleted
+	// channel_archive
+	// channel_unarchive
+	Type      string `json:"type"`
+	Channel   string `json:"channel"`
+	User      string `json:"user,omitempty"`
+	Timestamp string `json:"ts,omitempty"`
+}
+
+// ChannelRenameEvent represents the Channel rename event
+type ChannelRenameEvent struct {
+	Type      string            `json:"type"`
+	Channel   ChannelRenameInfo `json:"channel"`
+	Timestamp string            `json:"event_ts"`
+}
+
+// ChannelRenameInfo represents the information associated with a Channel rename event
+type ChannelRenameInfo struct {
+	ID      string `json:"id"`
+	Name    string `json:"name"`
+	Created string `json:"created"`
+}
+
+// ChannelHistoryChangedEvent represents the Channel history changed event
+type ChannelHistoryChangedEvent struct {
+	Type           string `json:"type"`
+	Latest         string `json:"latest"`
+	Timestamp      string `json:"ts"`
+	EventTimestamp string `json:"event_ts"`
+}
+
+// ChannelMarkedEvent represents the Channel marked event
+type ChannelMarkedEvent ChannelInfoEvent
+
+// ChannelLeftEvent represents the Channel left event
+type ChannelLeftEvent ChannelInfoEvent
+
+// ChannelDeletedEvent represents the Channel deleted event
+type ChannelDeletedEvent ChannelInfoEvent
+
+// ChannelArchiveEvent represents the Channel archive event
+type ChannelArchiveEvent ChannelInfoEvent
+
+// ChannelUnarchiveEvent represents the Channel unarchive event
+type ChannelUnarchiveEvent ChannelInfoEvent
diff --git a/vendor/github.com/slack-go/slack/websocket_desktop_notification.go b/vendor/github.com/slack-go/slack/websocket_desktop_notification.go
new file mode 100644
index 00000000..7c61abf7
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/websocket_desktop_notification.go
@@ -0,0 +1,19 @@
+package slack
+
+// DesktopNotificationEvent represents the update event for Desktop Notification.
+type DesktopNotificationEvent struct {
+	Type            string `json:"type"`
+	Title           string `json:"title"`
+	Subtitle        string `json:"subtitle"`
+	Message         string `json:"msg"`
+	Timestamp       string `json:"ts"`
+	Content         string `json:"content"`
+	Channel         string `json:"channel"`
+	LaunchURI       string `json:"launchUri"`
+	AvatarImage     string `json:"avatarImage"`
+	SsbFilename     string `json:"ssbFilename"`
+	ImageURI        string `json:"imageUri"`
+	IsShared        bool   `json:"is_shared"`
+	IsChannelInvite bool   `json:"is_channel_invite"`
+	EventTimestamp  string `json:"event_ts"`
+}
diff --git a/vendor/github.com/slack-go/slack/websocket_dm.go b/vendor/github.com/slack-go/slack/websocket_dm.go
new file mode 100644
index 00000000..98bf6f88
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/websocket_dm.go
@@ -0,0 +1,23 @@
+package slack
+
+// IMCreatedEvent represents the IM created event
+type IMCreatedEvent struct {
+	Type    string             `json:"type"`
+	User    string             `json:"user"`
+	Channel ChannelCreatedInfo `json:"channel"`
+}
+
+// IMHistoryChangedEvent represents the IM history changed event
+type IMHistoryChangedEvent ChannelHistoryChangedEvent
+
+// IMOpenEvent represents the IM open event
+type IMOpenEvent ChannelInfoEvent
+
+// IMCloseEvent represents the IM close event
+type IMCloseEvent ChannelInfoEvent
+
+// IMMarkedEvent represents the IM marked event
+type IMMarkedEvent ChannelInfoEvent
+
+// IMMarkedHistoryChanged represents the IM marked history changed event
+type IMMarkedHistoryChanged ChannelInfoEvent
diff --git a/vendor/github.com/slack-go/slack/websocket_dnd.go b/vendor/github.com/slack-go/slack/websocket_dnd.go
new file mode 100644
index 00000000..62ddea3a
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/websocket_dnd.go
@@ -0,0 +1,8 @@
+package slack
+
+// DNDUpdatedEvent represents the update event for Do Not Disturb
+type DNDUpdatedEvent struct {
+	Type   string    `json:"type"`
+	User   string    `json:"user"`
+	Status DNDStatus `json:"dnd_status"`
+}
diff --git a/vendor/github.com/slack-go/slack/websocket_files.go b/vendor/github.com/slack-go/slack/websocket_files.go
new file mode 100644
index 00000000..8c5bd4f8
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/websocket_files.go
@@ -0,0 +1,49 @@
+package slack
+
+// FileActionEvent represents the File action event
+type fileActionEvent struct {
+	Type           string `json:"type"`
+	EventTimestamp string `json:"event_ts"`
+	File           File   `json:"file"`
+	// FileID is used for FileDeletedEvent
+	FileID string `json:"file_id,omitempty"`
+}
+
+// FileCreatedEvent represents the File created event
+type FileCreatedEvent fileActionEvent
+
+// FileSharedEvent represents the File shared event
+type FileSharedEvent fileActionEvent
+
+// FilePublicEvent represents the File public event
+type FilePublicEvent fileActionEvent
+
+// FileUnsharedEvent represents the File unshared event
+type FileUnsharedEvent fileActionEvent
+
+// FileChangeEvent represents the File change event
+type FileChangeEvent fileActionEvent
+
+// FileDeletedEvent represents the File deleted event
+type FileDeletedEvent fileActionEvent
+
+// FilePrivateEvent represents the File private event
+type FilePrivateEvent fileActionEvent
+
+// FileCommentAddedEvent represents the File comment added event
+type FileCommentAddedEvent struct {
+	fileActionEvent
+	Comment Comment `json:"comment"`
+}
+
+// FileCommentEditedEvent represents the File comment edited event
+type FileCommentEditedEvent struct {
+	fileActionEvent
+	Comment Comment `json:"comment"`
+}
+
+// FileCommentDeletedEvent represents the File comment deleted event
+type FileCommentDeletedEvent struct {
+	fileActionEvent
+	Comment string `json:"comment"`
+}
diff --git a/vendor/github.com/slack-go/slack/websocket_groups.go b/vendor/github.com/slack-go/slack/websocket_groups.go
new file mode 100644
index 00000000..eb88985c
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/websocket_groups.go
@@ -0,0 +1,49 @@
+package slack
+
+// GroupCreatedEvent represents the Group created event
+type GroupCreatedEvent struct {
+	Type    string             `json:"type"`
+	User    string             `json:"user"`
+	Channel ChannelCreatedInfo `json:"channel"`
+}
+
+// XXX: Should we really do this? event.Group is probably nicer than event.Channel
+// even though the api returns "channel"
+
+// GroupMarkedEvent represents the Group marked event
+type GroupMarkedEvent ChannelInfoEvent
+
+// GroupOpenEvent represents the Group open event
+type GroupOpenEvent ChannelInfoEvent
+
+// GroupCloseEvent represents the Group close event
+type GroupCloseEvent ChannelInfoEvent
+
+// GroupArchiveEvent represents the Group archive event
+type GroupArchiveEvent ChannelInfoEvent
+
+// GroupUnarchiveEvent represents the Group unarchive event
+type GroupUnarchiveEvent ChannelInfoEvent
+
+// GroupLeftEvent represents the Group left event
+type GroupLeftEvent ChannelInfoEvent
+
+// GroupJoinedEvent represents the Group joined event
+type GroupJoinedEvent ChannelJoinedEvent
+
+// GroupRenameEvent represents the Group rename event
+type GroupRenameEvent struct {
+	Type      string          `json:"type"`
+	Group     GroupRenameInfo `json:"channel"`
+	Timestamp string          `json:"ts"`
+}
+
+// GroupRenameInfo represents the group info related to the renamed group
+type GroupRenameInfo struct {
+	ID      string `json:"id"`
+	Name    string `json:"name"`
+	Created string `json:"created"`
+}
+
+// GroupHistoryChangedEvent represents the Group history changed event
+type GroupHistoryChangedEvent ChannelHistoryChangedEvent
diff --git a/vendor/github.com/slack-go/slack/websocket_internals.go b/vendor/github.com/slack-go/slack/websocket_internals.go
new file mode 100644
index 00000000..3e1906ee
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/websocket_internals.go
@@ -0,0 +1,101 @@
+package slack
+
+import (
+	"fmt"
+	"time"
+)
+
+/**
+ * Internal events, created by this lib and not mapped to Slack APIs.
+ */
+
+// ConnectedEvent is used for when we connect to Slack
+type ConnectedEvent struct {
+	ConnectionCount int // 1 = first time, 2 = second time
+	Info            *Info
+}
+
+// ConnectionErrorEvent contains information about a connection error
+type ConnectionErrorEvent struct {
+	Attempt  int
+	Backoff  time.Duration // how long we'll wait before the next attempt
+	ErrorObj error
+}
+
+func (c *ConnectionErrorEvent) Error() string {
+	return c.ErrorObj.Error()
+}
+
+// ConnectingEvent contains information about our connection attempt
+type ConnectingEvent struct {
+	Attempt         int // 1 = first attempt, 2 = second attempt
+	ConnectionCount int
+}
+
+// DisconnectedEvent contains information about how we disconnected
+type DisconnectedEvent struct {
+	Intentional bool
+	Cause       error
+}
+
+// LatencyReport contains information about connection latency
+type LatencyReport struct {
+	Value time.Duration
+}
+
+// InvalidAuthEvent is used in case we can't even authenticate with the API
+type InvalidAuthEvent struct{}
+
+// UnmarshallingErrorEvent is used when there are issues deconstructing a response
+type UnmarshallingErrorEvent struct {
+	ErrorObj error
+}
+
+func (u UnmarshallingErrorEvent) Error() string {
+	return u.ErrorObj.Error()
+}
+
+// MessageTooLongEvent is used when sending a message that is too long
+type MessageTooLongEvent struct {
+	Message   OutgoingMessage
+	MaxLength int
+}
+
+func (m *MessageTooLongEvent) Error() string {
+	return fmt.Sprintf("Message too long (max %d characters)", m.MaxLength)
+}
+
+// RateLimitEvent is used when Slack warns that rate-limits are being hit.
+type RateLimitEvent struct{}
+
+func (e *RateLimitEvent) Error() string {
+	return "Messages are being sent too fast."
+}
+
+// OutgoingErrorEvent contains information in case there were errors sending messages
+type OutgoingErrorEvent struct {
+	Message  OutgoingMessage
+	ErrorObj error
+}
+
+func (o OutgoingErrorEvent) Error() string {
+	return o.ErrorObj.Error()
+}
+
+// IncomingEventError contains information about an unexpected error receiving a websocket event
+type IncomingEventError struct {
+	ErrorObj error
+}
+
+func (i *IncomingEventError) Error() string {
+	return i.ErrorObj.Error()
+}
+
+// AckErrorEvent i
+type AckErrorEvent struct {
+	ErrorObj error
+}
+
+func (a *AckErrorEvent) Error() string {
+	return a.ErrorObj.Error()
+}
diff --git a/vendor/github.com/slack-go/slack/websocket_managed_conn.go b/vendor/github.com/slack-go/slack/websocket_managed_conn.go
new file mode 100644
index 00000000..6395938c
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/websocket_managed_conn.go
@@ -0,0 +1,581 @@
+package slack
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	stdurl "net/url"
+	"reflect"
+	"time"
+
+	"github.com/gorilla/websocket"
+	"github.com/slack-go/slack/internal/errorsx"
+	"github.com/slack-go/slack/internal/timex"
+)
+
+// ManageConnection can be called on a Slack RTM instance returned by the
+// NewRTM method. It will connect to the slack RTM API and handle all incoming
+// and outgoing events. If a connection fails then it will attempt to reconnect
+// and will notify any listeners through an error event on the IncomingEvents
+// channel.
+//
+// If the connection ends and the disconnect was unintentional then this will
+// attempt to reconnect.
+//
+// This should only be called once per slack API! Otherwise expect undefined
+// behavior.
+//
+// The defined error events are located in websocket_internals.go.
+func (rtm *RTM) ManageConnection() {
+	var (
+		err  error
+		info *Info
+		conn *websocket.Conn
+	)
+
+	for connectionCount := 0; ; connectionCount++ {
+		// start trying to connect
+		// the returned err is already passed onto the IncomingEvents channel
+		if info, conn, err = rtm.connect(connectionCount, rtm.useRTMStart); err != nil {
+			// when the connection is unsuccessful its fatal, and we need to bail out.
+			rtm.Debugf("Failed to connect with RTM on try %d: %s", connectionCount, err)
+			rtm.disconnect()
+			return
+		}
+
+		// lock to prevent data races with Disconnect particularly around isConnected
+		// and conn.
+		rtm.mu.Lock()
+		rtm.conn = conn
+		rtm.info = info
+		rtm.mu.Unlock()
+
+		rtm.IncomingEvents <- RTMEvent{"connected", &ConnectedEvent{
+			ConnectionCount: connectionCount,
+			Info:            info,
+		}}
+
+		rtm.Debugf("RTM connection succeeded on try %d", connectionCount)
+
+		rawEvents := make(chan json.RawMessage)
+		// we're now connected so we can set up listeners
+		go rtm.handleIncomingEvents(rawEvents)
+		// this should be a blocking call until the connection has ended
+		rtm.handleEvents(rawEvents)
+
+		select {
+		case <-rtm.disconnected:
+			// after handle events returns we need to check if we're disconnected
+			// when this happens we need to cleanup the newly created connection.
+			if err = conn.Close(); err != nil {
+				rtm.Debugln("failed to close conn on disconnected RTM", err)
+			}
+			return
+		default:
+			// otherwise continue and run the loop again to reconnect
+		}
+	}
+}
+
+// connect attempts to connect to the slack websocket API. It handles any
+// errors that occur while connecting and will return once a connection
+// has been successfully opened.
+// If useRTMStart is false then it uses rtm.connect to create the connection,
+// otherwise it uses rtm.start.
+func (rtm *RTM) connect(connectionCount int, useRTMStart bool) (*Info, *websocket.Conn, error) {
+	const (
+		errInvalidAuth      = "invalid_auth"
+		errInactiveAccount  = "account_inactive"
+		errMissingAuthToken = "not_authed"
+	)
+
+	// used to provide exponential backoff wait time with jitter before trying
+	// to connect to slack again
+	boff := &backoff{
+		Max: 5 * time.Minute,
+	}
+
+	for {
+		var (
+			backoff time.Duration
+		)
+
+		// send connecting event
+		rtm.IncomingEvents <- RTMEvent{"connecting", &ConnectingEvent{
+			Attempt:         boff.attempts + 1,
+			ConnectionCount: connectionCount,
+		}}
+
+		// attempt to start the connection
+		info, conn, err := rtm.startRTMAndDial(useRTMStart)
+		if err == nil {
+			return info, conn, nil
+		}
+
+		// check for fatal errors
+		switch err.Error() {
+		case errInvalidAuth, errInactiveAccount, errMissingAuthToken:
+			rtm.Debugf("invalid auth when connecting with RTM: %s", err)
+			rtm.IncomingEvents <- RTMEvent{"invalid_auth", &InvalidAuthEvent{}}
+			return nil, nil, err
+		default:
+		}
+
+		switch actual := err.(type) {
+		case statusCodeError:
+			if actual.Code == http.StatusNotFound {
+				rtm.Debugf("invalid auth when connecting with RTM: %s", err)
+				rtm.IncomingEvents <- RTMEvent{"invalid_auth", &InvalidAuthEvent{}}
+				return nil, nil, err
+			}
+		case *RateLimitedError:
+			backoff = actual.RetryAfter
+		default:
+		}
+
+		backoff = timex.Max(backoff, boff.Duration())
+		// any other errors are treated as recoverable and we try again after
+		// sending the event along the IncomingEvents channel
+		rtm.IncomingEvents <- RTMEvent{"connection_error", &ConnectionErrorEvent{
+			Attempt:  boff.attempts,
+			Backoff:  backoff,
+			ErrorObj: err,
+		}}
+
+		// get time we should wait before attempting to connect again
+		rtm.Debugf("reconnection %d failed: %s reconnecting in %v\n", boff.attempts, err, backoff)
+
+		// wait for one of the following to occur,
+		// backoff duration has elapsed, killChannel is signalled, or
+		// the rtm finishes disconnecting.
+		select {
+		case <-time.After(backoff): // retry after the backoff.
+		case intentional := <-rtm.killChannel:
+			if intentional {
+				rtm.killConnection(intentional, ErrRTMDisconnected)
+				return nil, nil, ErrRTMDisconnected
+			}
+		case <-rtm.disconnected:
+			return nil, nil, ErrRTMDisconnected
+		}
+	}
+}
+
+// startRTMAndDial attempts to connect to the slack websocket. If useRTMStart is true,
+// then it returns the  full information returned by the "rtm.start" method on the
+// slack API. Else it uses the "rtm.connect" method to connect
+func (rtm *RTM) startRTMAndDial(useRTMStart bool) (info *Info, _ *websocket.Conn, err error) {
+	var (
+		url string
+	)
+
+	if useRTMStart {
+		rtm.Debugf("Starting RTM")
+		info, url, err = rtm.StartRTM()
+	} else {
+		rtm.Debugf("Connecting to RTM")
+		info, url, err = rtm.ConnectRTM()
+	}
+	if err != nil {
+		rtm.Debugf("Failed to start or connect to RTM: %s", err)
+		return nil, nil, err
+	}
+
+	// install connection parameters
+	u, err := stdurl.Parse(url)
+	if err != nil {
+		return nil, nil, err
+	}
+	u.RawQuery = rtm.connParams.Encode()
+	url = u.String()
+
+	rtm.Debugf("Dialing to websocket on url %s", url)
+	// Only use HTTPS for connections to prevent MITM attacks on the connection.
+	upgradeHeader := http.Header{}
+	upgradeHeader.Add("Origin", "https://api.slack.com")
+	dialer := websocket.DefaultDialer
+	if rtm.dialer != nil {
+		dialer = rtm.dialer
+	}
+	conn, _, err := dialer.Dial(url, upgradeHeader)
+	if err != nil {
+		rtm.Debugf("Failed to dial to the websocket: %s", err)
+		return nil, nil, err
+	}
+	return info, conn, err
+}
+
+// killConnection stops the websocket connection and signals to all goroutines
+// that they should cease listening to the connection for events.
+//
+// This should not be called directly! Instead a boolean value (true for
+// intentional, false otherwise) should be sent to the killChannel on the RTM.
+func (rtm *RTM) killConnection(intentional bool, cause error) (err error) {
+	rtm.Debugln("killing connection", cause)
+
+	if rtm.conn != nil {
+		err = rtm.conn.Close()
+	}
+
+	rtm.IncomingEvents <- RTMEvent{"disconnected", &DisconnectedEvent{Intentional: intentional, Cause: cause}}
+
+	if intentional {
+		rtm.disconnect()
+	}
+
+	return err
+}
+
+// handleEvents is a blocking function that handles all events. This sends
+// pings when asked to (on rtm.forcePing) and upon every given elapsed
+// interval. This also sends outgoing messages that are received from the RTM's
+// outgoingMessages channel. This also handles incoming raw events from the RTM
+// rawEvents channel.
+func (rtm *RTM) handleEvents(events chan json.RawMessage) {
+	ticker := time.NewTicker(rtm.pingInterval)
+	defer ticker.Stop()
+	for {
+		select {
+		// catch "stop" signal on channel close
+		case intentional := <-rtm.killChannel:
+			_ = rtm.killConnection(intentional, errorsx.String("signaled"))
+			return
+		// detect when the connection is dead.
+		case <-rtm.pingDeadman.C:
+			_ = rtm.killConnection(false, ErrRTMDeadman)
+			return
+		// send pings on ticker interval
+		case <-ticker.C:
+			if err := rtm.ping(); err != nil {
+				_ = rtm.killConnection(false, err)
+				return
+			}
+		case <-rtm.forcePing:
+			if err := rtm.ping(); err != nil {
+				_ = rtm.killConnection(false, err)
+				return
+			}
+		// listen for messages that need to be sent
+		case msg := <-rtm.outgoingMessages:
+			rtm.sendOutgoingMessage(msg)
+			// listen for incoming messages that need to be parsed
+		case rawEvent := <-events:
+			switch rtm.handleRawEvent(rawEvent) {
+			case rtmEventTypeGoodbye:
+				// kill the connection, but DO NOT RETURN, a follow up kill signal will
+				// be sent that still needs to be processed. this duplication is because
+				// the event reader restarts once it emits the goodbye event.
+				// unlike the other cases in this function a final read will be triggered
+				// against the connection which will emit a kill signal. if we return early
+				// this kill signal will be processed by the next connection.
+				_ = rtm.killConnection(false, ErrRTMGoodbye)
+			default:
+			}
+		}
+	}
+}
+
+// handleIncomingEvents monitors the RTM's opened websocket for any incoming
+// events. It pushes the raw events into the channel.
+//
+// This will stop executing once the RTM's when a fatal error is detected, or
+// a disconnect occurs.
+func (rtm *RTM) handleIncomingEvents(events chan json.RawMessage) {
+	for {
+		if err := rtm.receiveIncomingEvent(events); err != nil {
+			select {
+			case rtm.killChannel <- false:
+			case <-rtm.disconnected:
+			}
+			return
+		}
+	}
+}
+
+func (rtm *RTM) sendWithDeadline(msg interface{}) error {
+	// set a write deadline on the connection
+	if err := rtm.conn.SetWriteDeadline(time.Now().Add(10 * time.Second)); err != nil {
+		return err
+	}
+	if err := rtm.conn.WriteJSON(msg); err != nil {
+		return err
+	}
+	// remove write deadline
+	return rtm.conn.SetWriteDeadline(time.Time{})
+}
+
+// sendOutgoingMessage sends the given OutgoingMessage to the slack websocket.
+//
+// It does not currently detect if a outgoing message fails due to a disconnect
+// and instead lets a future failed 'PING' detect the failed connection.
+func (rtm *RTM) sendOutgoingMessage(msg OutgoingMessage) {
+	rtm.Debugln("Sending message:", msg)
+	if len([]rune(msg.Text)) > MaxMessageTextLength {
+		rtm.IncomingEvents <- RTMEvent{"outgoing_error", &MessageTooLongEvent{
+			Message:   msg,
+			MaxLength: MaxMessageTextLength,
+		}}
+		return
+	}
+
+	if err := rtm.sendWithDeadline(msg); err != nil {
+		rtm.IncomingEvents <- RTMEvent{"outgoing_error", &OutgoingErrorEvent{
+			Message:  msg,
+			ErrorObj: err,
+		}}
+	}
+}
+
+// ping sends a 'PING' message to the RTM's websocket. If the 'PING' message
+// fails to send then this returns an error signifying that the connection
+// should be considered disconnected.
+//
+// This does not handle incoming 'PONG' responses but does store the time of
+// each successful 'PING' send so latency can be detected upon a 'PONG'
+// response.
+func (rtm *RTM) ping() error {
+	id := rtm.idGen.Next()
+	rtm.Debugln("Sending PING ", id)
+	msg := &Ping{ID: id, Type: "ping", Timestamp: time.Now().Unix()}
+
+	if err := rtm.sendWithDeadline(msg); err != nil {
+		rtm.Debugf("RTM Error sending 'PING %d': %s", id, err.Error())
+		return err
+	}
+	return nil
+}
+
+// receiveIncomingEvent attempts to receive an event from the RTM's websocket.
+// This will block until a frame is available from the websocket.
+// If the read from the websocket results in a fatal error, this function will return non-nil.
+func (rtm *RTM) receiveIncomingEvent(events chan json.RawMessage) error {
+	event := json.RawMessage{}
+	err := rtm.conn.ReadJSON(&event)
+
+	// check if the connection was closed.
+	if websocket.IsUnexpectedCloseError(err) {
+		return err
+	}
+
+	switch {
+	case err == io.ErrUnexpectedEOF:
+		// EOF's don't seem to signify a failed connection so instead we ignore
+		// them here and detect a failed connection upon attempting to send a
+		// 'PING' message
+
+		// trigger a 'PING' to detect potential websocket disconnect
+		select {
+		case rtm.forcePing <- true:
+		case <-rtm.disconnected:
+		}
+	case err != nil:
+		// All other errors from ReadJSON come from NextReader, and should
+		// kill the read loop and force a reconnect.
+		rtm.IncomingEvents <- RTMEvent{"incoming_error", &IncomingEventError{
+			ErrorObj: err,
+		}}
+
+		return err
+	case len(event) == 0:
+		rtm.Debugln("Received empty event")
+	default:
+		rtm.Debugln("Incoming Event:", string(event))
+		select {
+		case events <- event:
+		case <-rtm.disconnected:
+			rtm.Debugln("disonnected while attempting to send raw event")
+		}
+	}
+
+	return nil
+}
+
+// handleRawEvent takes a raw JSON message received from the slack websocket
+// and handles the encoded event.
+// returns the event type of the message.
+func (rtm *RTM) handleRawEvent(rawEvent json.RawMessage) string {
+	event := &Event{}
+	err := json.Unmarshal(rawEvent, event)
+	if err != nil {
+		rtm.IncomingEvents <- RTMEvent{"unmarshalling_error", &UnmarshallingErrorEvent{err}}
+		return ""
+	}
+
+	switch event.Type {
+	case rtmEventTypeAck:
+		rtm.handleAck(rawEvent)
+	case rtmEventTypeHello:
+		rtm.IncomingEvents <- RTMEvent{"hello", &HelloEvent{}}
+	case rtmEventTypePong:
+		rtm.handlePong(rawEvent)
+	case rtmEventTypeGoodbye:
+		// just return the event type up for goodbye, will be handled by caller.
+	default:
+		rtm.handleEvent(event.Type, rawEvent)
+	}
+
+	return event.Type
+}
+
+// handleAck handles an incoming 'ACK' message.
+func (rtm *RTM) handleAck(event json.RawMessage) {
+	ack := &AckMessage{}
+	if err := json.Unmarshal(event, ack); err != nil {
+		rtm.Debugln("RTM Error unmarshalling 'ack' event:", err)
+		rtm.Debugln(" -> Erroneous 'ack' event:", string(event))
+		return
+	}
+
+	if ack.Ok {
+		rtm.IncomingEvents <- RTMEvent{"ack", ack}
+	} else if ack.RTMResponse.Error != nil {
+		// As there is no documentation for RTM error-codes, this
+		// identification of a rate-limit warning is very brittle.
+		if ack.RTMResponse.Error.Code == -1 && ack.RTMResponse.Error.Msg == "slow down, too many messages..." {
+			rtm.IncomingEvents <- RTMEvent{"ack_error", &RateLimitEvent{}}
+		} else {
+			rtm.IncomingEvents <- RTMEvent{"ack_error", &AckErrorEvent{ack.Error}}
+		}
+	} else {
+		rtm.IncomingEvents <- RTMEvent{"ack_error", &AckErrorEvent{fmt.Errorf("ack decode failure")}}
+	}
+}
+
+// handlePong handles an incoming 'PONG' message which should be in response to
+// a previously sent 'PING' message. This is then used to compute the
+// connection's latency.
+func (rtm *RTM) handlePong(event json.RawMessage) {
+	var (
+		p Pong
+	)
+
+	rtm.resetDeadman()
+
+	if err := json.Unmarshal(event, &p); err != nil {
+		rtm.Client.log.Println("RTM Error unmarshalling 'pong' event:", err)
+		return
+	}
+
+	latency := time.Since(time.Unix(p.Timestamp, 0))
+	rtm.IncomingEvents <- RTMEvent{"latency_report", &LatencyReport{Value: latency}}
+}
+
+// handleEvent is the "default" response to an event that does not have a
+// special case. It matches the command's name to a mapping of defined events
+// and then sends the corresponding event struct to the IncomingEvents channel.
+// If the event type is not found or the event cannot be unmarshalled into the
+// correct struct then this sends an UnmarshallingErrorEvent to the
+// IncomingEvents channel.
+func (rtm *RTM) handleEvent(typeStr string, event json.RawMessage) {
+	v, exists := EventMapping[typeStr]
+	if !exists {
+		rtm.Debugf("RTM Error - received unmapped event %q: %s\n", typeStr, string(event))
+		err := fmt.Errorf("RTM Error: Received unmapped event %q: %s", typeStr, string(event))
+		rtm.IncomingEvents <- RTMEvent{"unmarshalling_error", &UnmarshallingErrorEvent{err}}
+		return
+	}
+	t := reflect.TypeOf(v)
+	recvEvent := reflect.New(t).Interface()
+	err := json.Unmarshal(event, recvEvent)
+	if err != nil {
+		rtm.Debugf("RTM Error, could not unmarshall event %q: %s\n", typeStr, string(event))
+		err := fmt.Errorf("RTM Error: Could not unmarshall event %q: %s", typeStr, string(event))
+		rtm.IncomingEvents <- RTMEvent{"unmarshalling_error", &UnmarshallingErrorEvent{err}}
+		return
+	}
+	rtm.IncomingEvents <- RTMEvent{typeStr, recvEvent}
+}
+
+// EventMapping holds a mapping of event names to their corresponding struct
+// implementations. The structs should be instances of the unmarshalling
+// target for the matching event type.
+var EventMapping = map[string]interface{}{
+	"message":         MessageEvent{},
+	"presence_change": PresenceChangeEvent{},
+	"user_typing":     UserTypingEvent{},
+
+	"channel_marked":          ChannelMarkedEvent{},
+	"channel_created":         ChannelCreatedEvent{},
+	"channel_joined":          ChannelJoinedEvent{},
+	"channel_left":            ChannelLeftEvent{},
+	"channel_deleted":         ChannelDeletedEvent{},
+	"channel_rename":          ChannelRenameEvent{},
+	"channel_archive":         ChannelArchiveEvent{},
+	"channel_unarchive":       ChannelUnarchiveEvent{},
+	"channel_history_changed": ChannelHistoryChangedEvent{},
+
+	"dnd_updated":      DNDUpdatedEvent{},
+	"dnd_updated_user": DNDUpdatedEvent{},
+
+	"im_created":         IMCreatedEvent{},
+	"im_open":            IMOpenEvent{},
+	"im_close":           IMCloseEvent{},
+	"im_marked":          IMMarkedEvent{},
+	"im_history_changed": IMHistoryChangedEvent{},
+
+	"group_marked":          GroupMarkedEvent{},
+	"group_open":            GroupOpenEvent{},
+	"group_joined":          GroupJoinedEvent{},
+	"group_left":            GroupLeftEvent{},
+	"group_close":           GroupCloseEvent{},
+	"group_rename":          GroupRenameEvent{},
+	"group_archive":         GroupArchiveEvent{},
+	"group_unarchive":       GroupUnarchiveEvent{},
+	"group_history_changed": GroupHistoryChangedEvent{},
+
+	"file_created":         FileCreatedEvent{},
+	"file_shared":          FileSharedEvent{},
+	"file_unshared":        FileUnsharedEvent{},
+	"file_public":          FilePublicEvent{},
+	"file_private":         FilePrivateEvent{},
+	"file_change":          FileChangeEvent{},
+	"file_deleted":         FileDeletedEvent{},
+	"file_comment_added":   FileCommentAddedEvent{},
+	"file_comment_edited":  FileCommentEditedEvent{},
+	"file_comment_deleted": FileCommentDeletedEvent{},
+
+	"pin_added":   PinAddedEvent{},
+	"pin_removed": PinRemovedEvent{},
+
+	"star_added":   StarAddedEvent{},
+	"star_removed": StarRemovedEvent{},
+
+	"reaction_added":   ReactionAddedEvent{},
+	"reaction_removed": ReactionRemovedEvent{},
+
+	"pref_change": PrefChangeEvent{},
+
+	"team_join":              TeamJoinEvent{},
+	"team_rename":            TeamRenameEvent{},
+	"team_pref_change":       TeamPrefChangeEvent{},
+	"team_domain_change":     TeamDomainChangeEvent{},
+	"team_migration_started": TeamMigrationStartedEvent{},
+
+	"manual_presence_change": ManualPresenceChangeEvent{},
+
+	"user_change": UserChangeEvent{},
+
+	"emoji_changed": EmojiChangedEvent{},
+
+	"commands_changed": CommandsChangedEvent{},
+
+	"email_domain_changed": EmailDomainChangedEvent{},
+
+	"bot_added":   BotAddedEvent{},
+	"bot_changed": BotChangedEvent{},
+
+	"accounts_changed": AccountsChangedEvent{},
+
+	"reconnect_url": ReconnectUrlEvent{},
+
+	"member_joined_channel": MemberJoinedChannelEvent{},
+	"member_left_channel":   MemberLeftChannelEvent{},
+
+	"subteam_created":      SubteamCreatedEvent{},
+	"subteam_self_added":   SubteamSelfAddedEvent{},
+	"subteam_self_removed": SubteamSelfRemovedEvent{},
+	"subteam_updated":      SubteamUpdatedEvent{},
+
+	"desktop_notification": DesktopNotificationEvent{},
+}
diff --git a/vendor/github.com/slack-go/slack/websocket_misc.go b/vendor/github.com/slack-go/slack/websocket_misc.go
new file mode 100644
index 00000000..65a8bb65
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/websocket_misc.go
@@ -0,0 +1,141 @@
+package slack
+
+import (
+	"encoding/json"
+	"fmt"
+)
+
+// AckMessage is used for messages received in reply to other messages
+type AckMessage struct {
+	ReplyTo   int    `json:"reply_to"`
+	Timestamp string `json:"ts"`
+	Text      string `json:"text"`
+	RTMResponse
+}
+
+// RTMResponse encapsulates response details as returned by the Slack API
+type RTMResponse struct {
+	Ok    bool      `json:"ok"`
+	Error *RTMError `json:"error"`
+}
+
+// RTMError encapsulates error information as returned by the Slack API
+type RTMError struct {
+	Code int
+	Msg  string
+}
+
+func (s RTMError) Error() string {
+	return fmt.Sprintf("Code %d - %s", s.Code, s.Msg)
+}
+
+// MessageEvent represents a Slack Message (used as the event type for an incoming message)
+type MessageEvent Message
+
+// RTMEvent is the main wrapper. You will find all the other messages attached
+type RTMEvent struct {
+	Type string
+	Data interface{}
+}
+
+// HelloEvent represents the hello event
+type HelloEvent struct{}
+
+// PresenceChangeEvent represents the presence change event
+type PresenceChangeEvent struct {
+	Type     string   `json:"type"`
+	Presence string   `json:"presence"`
+	User     string   `json:"user"`
+	Users    []string `json:"users"`
+}
+
+// UserTypingEvent represents the user typing event
+type UserTypingEvent struct {
+	Type    string `json:"type"`
+	User    string `json:"user"`
+	Channel string `json:"channel"`
+}
+
+// PrefChangeEvent represents a user preferences change event
+type PrefChangeEvent struct {
+	Type  string          `json:"type"`
+	Name  string          `json:"name"`
+	Value json.RawMessage `json:"value"`
+}
+
+// ManualPresenceChangeEvent represents the manual presence change event
+type ManualPresenceChangeEvent struct {
+	Type     string `json:"type"`
+	Presence string `json:"presence"`
+}
+
+// UserChangeEvent represents the user change event
+type UserChangeEvent struct {
+	Type string `json:"type"`
+	User User   `json:"user"`
+}
+
+// EmojiChangedEvent represents the emoji changed event
+type EmojiChangedEvent struct {
+	Type           string   `json:"type"`
+	SubType        string   `json:"subtype"`
+	Name           string   `json:"name"`
+	Names          []string `json:"names"`
+	Value          string   `json:"value"`
+	EventTimestamp string   `json:"event_ts"`
+}
+
+// CommandsChangedEvent represents the commands changed event
+type CommandsChangedEvent struct {
+	Type           string `json:"type"`
+	EventTimestamp string `json:"event_ts"`
+}
+
+// EmailDomainChangedEvent represents the email domain changed event
+type EmailDomainChangedEvent struct {
+	Type           string `json:"type"`
+	EventTimestamp string `json:"event_ts"`
+	EmailDomain    string `json:"email_domain"`
+}
+
+// BotAddedEvent represents the bot added event
+type BotAddedEvent struct {
+	Type string `json:"type"`
+	Bot  Bot    `json:"bot"`
+}
+
+// BotChangedEvent represents the bot changed event
+type BotChangedEvent struct {
+	Type string `json:"type"`
+	Bot  Bot    `json:"bot"`
+}
+
+// AccountsChangedEvent represents the accounts changed event
+type AccountsChangedEvent struct {
+	Type string `json:"type"`
+}
+
+// ReconnectUrlEvent represents the receiving reconnect url event
+type ReconnectUrlEvent struct {
+	Type string `json:"type"`
+	URL  string `json:"url"`
+}
+
+// MemberJoinedChannelEvent, a user joined a public or private channel
+type MemberJoinedChannelEvent struct {
+	Type        string `json:"type"`
+	User        string `json:"user"`
+	Channel     string `json:"channel"`
+	ChannelType string `json:"channel_type"`
+	Team        string `json:"team"`
+	Inviter     string `json:"inviter"`
+}
+
+// MemberLeftChannelEvent a user left a public or private channel
+type MemberLeftChannelEvent struct {
+	Type        string `json:"type"`
+	User        string `json:"user"`
+	Channel     string `json:"channel"`
+	ChannelType string `json:"channel_type"`
+	Team        string `json:"team"`
+}
diff --git a/vendor/github.com/slack-go/slack/websocket_pins.go b/vendor/github.com/slack-go/slack/websocket_pins.go
new file mode 100644
index 00000000..95445e28
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/websocket_pins.go
@@ -0,0 +1,16 @@
+package slack
+
+type pinEvent struct {
+	Type           string `json:"type"`
+	User           string `json:"user"`
+	Item           Item   `json:"item"`
+	Channel        string `json:"channel_id"`
+	EventTimestamp string `json:"event_ts"`
+	HasPins        bool   `json:"has_pins,omitempty"`
+}
+
+// PinAddedEvent represents the Pin added event
+type PinAddedEvent pinEvent
+
+// PinRemovedEvent represents the Pin removed event
+type PinRemovedEvent pinEvent
diff --git a/vendor/github.com/slack-go/slack/websocket_reactions.go b/vendor/github.com/slack-go/slack/websocket_reactions.go
new file mode 100644
index 00000000..e4973878
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/websocket_reactions.go
@@ -0,0 +1,25 @@
+package slack
+
+// reactionItem is a lighter-weight item than is returned by the reactions list.
+type reactionItem struct {
+	Type        string `json:"type"`
+	Channel     string `json:"channel,omitempty"`
+	File        string `json:"file,omitempty"`
+	FileComment string `json:"file_comment,omitempty"`
+	Timestamp   string `json:"ts,omitempty"`
+}
+
+type reactionEvent struct {
+	Type           string       `json:"type"`
+	User           string       `json:"user"`
+	ItemUser       string       `json:"item_user"`
+	Item           reactionItem `json:"item"`
+	Reaction       string       `json:"reaction"`
+	EventTimestamp string       `json:"event_ts"`
+}
+
+// ReactionAddedEvent represents the Reaction added event
+type ReactionAddedEvent reactionEvent
+
+// ReactionRemovedEvent represents the Reaction removed event
+type ReactionRemovedEvent reactionEvent
diff --git a/vendor/github.com/slack-go/slack/websocket_stars.go b/vendor/github.com/slack-go/slack/websocket_stars.go
new file mode 100644
index 00000000..e0f2dda3
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/websocket_stars.go
@@ -0,0 +1,14 @@
+package slack
+
+type starEvent struct {
+	Type           string      `json:"type"`
+	User           string      `json:"user"`
+	Item           StarredItem `json:"item"`
+	EventTimestamp string      `json:"event_ts"`
+}
+
+// StarAddedEvent represents the Star added event
+type StarAddedEvent starEvent
+
+// StarRemovedEvent represents the Star removed event
+type StarRemovedEvent starEvent
diff --git a/vendor/github.com/slack-go/slack/websocket_subteam.go b/vendor/github.com/slack-go/slack/websocket_subteam.go
new file mode 100644
index 00000000..a23b274c
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/websocket_subteam.go
@@ -0,0 +1,35 @@
+package slack
+
+// SubteamCreatedEvent represents the Subteam created event
+type SubteamCreatedEvent struct {
+	Type    string    `json:"type"`
+	Subteam UserGroup `json:"subteam"`
+}
+
+// SubteamCreatedEvent represents the membership of an existing User Group has changed event
+type SubteamMembersChangedEvent struct {
+	Type               string   `json:"type"`
+	SubteamID          string   `json:"subteam_id"`
+	TeamID             string   `json:"team_id"`
+	DatePreviousUpdate JSONTime `json:"date_previous_update"`
+	DateUpdate         JSONTime `json:"date_update"`
+	AddedUsers         []string `json:"added_users"`
+	AddedUsersCount    string   `json:"added_users_count"`
+	RemovedUsers       []string `json:"removed_users"`
+	RemovedUsersCount  string   `json:"removed_users_count"`
+}
+
+// SubteamSelfAddedEvent represents an event of you have been added to a User Group
+type SubteamSelfAddedEvent struct {
+	Type      string `json:"type"`
+	SubteamID string `json:"subteam_id"`
+}
+
+// SubteamSelfRemovedEvent represents an event of you have been removed from a User Group
+type SubteamSelfRemovedEvent SubteamSelfAddedEvent
+
+// SubteamUpdatedEvent represents an event of an existing User Group has been updated or its members changed
+type SubteamUpdatedEvent struct {
+	Type    string    `json:"type"`
+	Subteam UserGroup `json:"subteam"`
+}
diff --git a/vendor/github.com/slack-go/slack/websocket_teams.go b/vendor/github.com/slack-go/slack/websocket_teams.go
new file mode 100644
index 00000000..3898c833
--- /dev/null
+++ b/vendor/github.com/slack-go/slack/websocket_teams.go
@@ -0,0 +1,33 @@
+package slack
+
+// TeamJoinEvent represents the Team join event
+type TeamJoinEvent struct {
+	Type string `json:"type"`
+	User User   `json:"user"`
+}
+
+// TeamRenameEvent represents the Team rename event
+type TeamRenameEvent struct {
+	Type           string `json:"type"`
+	Name           string `json:"name,omitempty"`
+	EventTimestamp string `json:"event_ts,omitempty"`
+}
+
+// TeamPrefChangeEvent represents the Team preference change event
+type TeamPrefChangeEvent struct {
+	Type  string   `json:"type"`
+	Name  string   `json:"name,omitempty"`
+	Value []string `json:"value,omitempty"`
+}
+
+// TeamDomainChangeEvent represents the Team domain change event
+type TeamDomainChangeEvent struct {
+	Type   string `json:"type"`
+	URL    string `json:"url"`
+	Domain string `json:"domain"`
+}
+
+// TeamMigrationStartedEvent represents the Team migration started event
+type TeamMigrationStartedEvent struct {
+	Type string `json:"type"`
+}