Update dependencies (#886)

56 files changed, 2039 insertions, 615 deletions

diff --git a/vendor/github.com/nlopes/slack/.travis.yml b/vendor/github.com/nlopes/slack/.travis.yml
index e4b9c754..ed99d9ef 100644
--- a/vendor/github.com/nlopes/slack/.travis.yml
+++ b/vendor/github.com/nlopes/slack/.travis.yml
@@ -1,12 +1,9 @@
 language: go
 
-go:
-  - 1.7.x
-  - 1.8.x
-  - 1.9.x
-  - 1.10.x
-  - 1.11.x
-  - tip
+env:
+  - GO111MODULE=on
+
+install: true
 
 before_install:
   - export PATH=$HOME/gopath/bin:$PATH
@@ -20,6 +17,19 @@ script:
 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: "tip"
+    script: go test -v -mod=vendor ./...
 
 git:
   depth: 10
diff --git a/vendor/github.com/nlopes/slack/CHANGELOG.md b/vendor/github.com/nlopes/slack/CHANGELOG.md
index 63309f23..48bcce55 100644
--- a/vendor/github.com/nlopes/slack/CHANGELOG.md
+++ b/vendor/github.com/nlopes/slack/CHANGELOG.md
@@ -1,3 +1,20 @@
+### 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.

diff --git a/vendor/github.com/nlopes/slack/Gopkg.lock b/vendor/github.com/nlopes/slack/Gopkg.lock
deleted file mode 100644
index 9c33d0dc..00000000
--- a/vendor/github.com/nlopes/slack/Gopkg.lock
+++ /dev/null
@@ -1,39 +0,0 @@
-# This file is autogenerated, do not edit; changes may be undone by the next 'dep ensure'.
-
-
-[[projects]]
-  name = "github.com/davecgh/go-spew"
-  packages = ["spew"]
-  revision = "346938d642f2ec3594ed81d874461961cd0faa76"
-  version = "v1.1.0"
-
-[[projects]]
-  name = "github.com/gorilla/websocket"
-  packages = ["."]
-  revision = "ea4d1f681babbce9545c9c5f3d5194a789c89f5b"
-  version = "v1.2.0"
-
-[[projects]]
-  name = "github.com/pkg/errors"
-  packages = ["."]
-  revision = "645ef00459ed84a119197bfb8d8205042c6df63d"
-  version = "v0.8.0"
-
-[[projects]]
-  name = "github.com/pmezard/go-difflib"
-  packages = ["difflib"]
-  revision = "792786c7400a136282c1664665ae0a8db921c6c2"
-  version = "v1.0.0"
-
-[[projects]]
-  name = "github.com/stretchr/testify"
-  packages = ["assert"]
-  revision = "f35b8ab0b5a2cef36673838d662e249dd9c94686"
-  version = "v1.2.2"
-
-[solve-meta]
-  analyzer-name = "dep"
-  analyzer-version = 1
-  inputs-digest = "596fa546322c2a1e9708a10c9f39aca2e04792b477fab86fb2899fbaab776070"
-  solver-name = "gps-cdcl"
-  solver-version = 1
diff --git a/vendor/github.com/nlopes/slack/Gopkg.toml b/vendor/github.com/nlopes/slack/Gopkg.toml
deleted file mode 100644
index 257870d6..00000000
--- a/vendor/github.com/nlopes/slack/Gopkg.toml
+++ /dev/null
@@ -1,17 +0,0 @@
-ignored = ["github.com/lusis/slack-test"]
-
-[[constraint]]
-  name = "github.com/gorilla/websocket"
-  version = "1.2.0"
-
-[[constraint]]
-  name = "github.com/stretchr/testify"
-  version = "1.2.1"
-
-[[constraint]]
-  name = "github.com/pkg/errors"
-  version = "0.8.0"
-
-[prune]
-  go-tests = true
-  unused-packages = true
diff --git a/vendor/github.com/nlopes/slack/README.md b/vendor/github.com/nlopes/slack/README.md
index b4148231..a5e8e5ef 100644
--- a/vendor/github.com/nlopes/slack/README.md
+++ b/vendor/github.com/nlopes/slack/README.md
@@ -35,7 +35,7 @@ func main() {
 	api := slack.New("YOUR_TOKEN_HERE")
 	// If you set debugging, it will log all requests to the console
 	// Useful when encountering issues
-	// api.SetDebug(true)
+	// slack.New("YOUR_TOKEN_HERE", slack.OptionDebug(true))
 	groups, err := api.GetGroups(false)
 	if err != nil {
 		fmt.Printf("%s\n", err)
diff --git a/vendor/github.com/nlopes/slack/admin.go b/vendor/github.com/nlopes/slack/admin.go
index db44aa38..d51426b5 100644
--- a/vendor/github.com/nlopes/slack/admin.go
+++ b/vendor/github.com/nlopes/slack/admin.go
@@ -2,28 +2,19 @@ package slack
 
 import (
 	"context"
-	"errors"
 	"fmt"
 	"net/url"
+	"strings"
 )
 
-type adminResponse struct {
-	OK    bool   `json:"ok"`
-	Error string `json:"error"`
-}
-
-func adminRequest(ctx context.Context, client httpClient, method string, teamName string, values url.Values, d debug) (*adminResponse, error) {
-	adminResponse := &adminResponse{}
-	err := parseAdminResponse(ctx, client, method, teamName, values, adminResponse, d)
+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 nil, err
+		return err
 	}
 
-	if !adminResponse.OK {
-		return nil, errors.New(adminResponse.Error)
-	}
-
-	return adminResponse, nil
+	return resp.Err()
 }
 
 // DisableUser disabled a user account, given a user ID
@@ -40,9 +31,8 @@ func (api *Client) DisableUserContext(ctx context.Context, teamName string, uid
 		"_attempts":  {"1"},
 	}
 
-	_, err := adminRequest(ctx, api.httpclient, "setInactive", teamName, values, api)
-	if err != nil {
-		return fmt.Errorf("Failed to disable user with id '%s': %s", uid, err)
+	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
@@ -67,7 +57,7 @@ func (api *Client) InviteGuestContext(ctx context.Context, teamName, channel, fi
 		"_attempts":        {"1"},
 	}
 
-	_, err := adminRequest(ctx, api.httpclient, "invite", teamName, values, api)
+	err := api.adminRequest(ctx, "invite", teamName, values)
 	if err != nil {
 		return fmt.Errorf("Failed to invite single-channel guest: %s", err)
 	}
@@ -94,7 +84,7 @@ func (api *Client) InviteRestrictedContext(ctx context.Context, teamName, channe
 		"_attempts":  {"1"},
 	}
 
-	_, err := adminRequest(ctx, api.httpclient, "invite", teamName, values, api)
+	err := api.adminRequest(ctx, "invite", teamName, values)
 	if err != nil {
 		return fmt.Errorf("Failed to restricted account: %s", err)
 	}
@@ -118,7 +108,7 @@ func (api *Client) InviteToTeamContext(ctx context.Context, teamName, firstName,
 		"_attempts":  {"1"},
 	}
 
-	_, err := adminRequest(ctx, api.httpclient, "invite", teamName, values, api)
+	err := api.adminRequest(ctx, "invite", teamName, values)
 	if err != nil {
 		return fmt.Errorf("Failed to invite to team: %s", err)
 	}
@@ -140,7 +130,7 @@ func (api *Client) SetRegularContext(ctx context.Context, teamName, user string)
 		"_attempts":  {"1"},
 	}
 
-	_, err := adminRequest(ctx, api.httpclient, "setRegular", teamName, values, api)
+	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)
 	}
@@ -162,7 +152,7 @@ func (api *Client) SendSSOBindingEmailContext(ctx context.Context, teamName, use
 		"_attempts":  {"1"},
 	}
 
-	_, err := adminRequest(ctx, api.httpclient, "sendSSOBind", teamName, values, api)
+	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)
 	}
@@ -185,7 +175,7 @@ func (api *Client) SetUltraRestrictedContext(ctx context.Context, teamName, uid,
 		"_attempts":  {"1"},
 	}
 
-	_, err := adminRequest(ctx, api.httpclient, "setUltraRestricted", teamName, values, api)
+	err := api.adminRequest(ctx, "setUltraRestricted", teamName, values)
 	if err != nil {
 		return fmt.Errorf("Failed to ultra-restrict account: %s", err)
 	}
@@ -194,22 +184,23 @@ func (api *Client) SetUltraRestrictedContext(ctx context.Context, teamName, uid,
 }
 
 // SetRestricted converts a user into a restricted account
-func (api *Client) SetRestricted(teamName, uid string) error {
-	return api.SetRestrictedContext(context.Background(), teamName, uid)
+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) error {
+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 := adminRequest(ctx, api.httpclient, "setRestricted", teamName, values, api)
+	err := api.adminRequest(ctx, "setRestricted", teamName, values)
 	if err != nil {
-		return fmt.Errorf("Failed to restrict account: %s", err)
+		return fmt.Errorf("failed to restrict account: %s", err)
 	}
 
 	return nil
diff --git a/vendor/github.com/nlopes/slack/attachments.go b/vendor/github.com/nlopes/slack/attachments.go
index 06f59fa3..cf8b5c67 100644
--- a/vendor/github.com/nlopes/slack/attachments.go
+++ b/vendor/github.com/nlopes/slack/attachments.go
@@ -17,7 +17,7 @@ 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            string                        `json:"type"`                       // Required. Must be set to "button" or "select".
+	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.
@@ -28,6 +28,11 @@ type AttachmentAction struct {
 	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.
@@ -45,13 +50,6 @@ type AttachmentActionOptionGroup struct {
 // DEPRECATED: use InteractionCallback
 type AttachmentActionCallback InteractionCallback
 
-// ActionCallback specific fields for the action callback.
-type ActionCallback struct {
-	MessageTs    string             `json:"message_ts"`
-	AttachmentID string             `json:"attachment_id"`
-	Actions      []AttachmentAction `json:"actions"`
-}
-
 // ConfirmationField are used to ask users to confirm actions
 type ConfirmationField struct {
 	Title       string `json:"title,omitempty"`        // Optional.
diff --git a/vendor/github.com/nlopes/slack/auth.go b/vendor/github.com/nlopes/slack/auth.go
index f8fe1f9d..dc1dbcdf 100644
--- a/vendor/github.com/nlopes/slack/auth.go
+++ b/vendor/github.com/nlopes/slack/auth.go
@@ -12,9 +12,9 @@ type AuthRevokeResponse struct {
 }
 
 // authRequest sends the actual request, and unmarshals the response
-func authRequest(ctx context.Context, client httpClient, path string, values url.Values, d debug) (*AuthRevokeResponse, error) {
+func (api *Client) authRequest(ctx context.Context, path string, values url.Values) (*AuthRevokeResponse, error) {
 	response := &AuthRevokeResponse{}
-	err := postSlackMethod(ctx, client, path, values, response, d)
+	err := api.postMethod(ctx, path, values, response)
 	if err != nil {
 		return nil, err
 	}
@@ -36,5 +36,5 @@ func (api *Client) SendAuthRevokeContext(ctx context.Context, token string) (*Au
 		"token": {token},
 	}
 
-	return authRequest(ctx, api.httpclient, "auth.revoke", values, api)
+	return api.authRequest(ctx, "auth.revoke", values)
 }
diff --git a/vendor/github.com/nlopes/slack/backoff.go b/vendor/github.com/nlopes/slack/backoff.go
index 197bce2e..2ba697e7 100644
--- a/vendor/github.com/nlopes/slack/backoff.go
+++ b/vendor/github.com/nlopes/slack/backoff.go
@@ -1,7 +1,6 @@
 package slack
 
 import (
-	"math"
 	"math/rand"
 	"time"
 )
@@ -14,41 +13,42 @@ import (
 // conjunction with the time package.
 type backoff struct {
 	attempts int
-	//Factor is the multiplying factor for each increment step
-	Factor float64
-	//Jitter eases contention by randomizing backoff steps
-	Jitter bool
-	//Min and Max are the minimum and maximum values of the counter
-	Min, Max time.Duration
+	// 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() time.Duration {
-	//Zero-values are nonsensical, so we use
-	//them to apply defaults
-	if b.Min == 0 {
-		b.Min = 100 * time.Millisecond
-	}
+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.Factor == 0 {
-		b.Factor = 2
+
+	if b.Initial == 0 {
+		b.Initial = 100 * time.Millisecond
 	}
-	//calculate this duration
-	dur := float64(b.Min) * math.Pow(b.Factor, float64(b.attempts))
-	if b.Jitter {
-		dur = rand.Float64()*(dur-float64(b.Min)) + float64(b.Min)
+
+	// calculate this duration
+	if dur = time.Duration(1 << uint(b.attempts)); dur > 0 {
+		dur = dur * b.Initial
+	} else {
+		dur = b.Max
 	}
-	//cap!
-	if dur > float64(b.Max) {
-		return b.Max
+
+	if b.Jitter > 0 {
+		dur = dur + time.Duration(rand.Intn(int(b.Jitter)))
 	}
-	//bump attempts count
+
+	// bump attempts count
 	b.attempts++
-	//return as a time.Duration
-	return time.Duration(dur)
+
+	return dur
 }
 
 //Resets the current value of the counter back to Min
diff --git a/vendor/github.com/nlopes/slack/block.go b/vendor/github.com/nlopes/slack/block.go
new file mode 100644
index 00000000..1fc7fece
--- /dev/null
+++ b/vendor/github.com/nlopes/slack/block.go
@@ -0,0 +1,71 @@
+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"
+)
+
+// 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"`
+	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/nlopes/slack/block_action.go b/vendor/github.com/nlopes/slack/block_action.go
new file mode 100644
index 00000000..fe46a95c
--- /dev/null
+++ b/vendor/github.com/nlopes/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/nlopes/slack/block_context.go b/vendor/github.com/nlopes/slack/block_context.go
new file mode 100644
index 00000000..c37bf27e
--- /dev/null
+++ b/vendor/github.com/nlopes/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/nlopes/slack/block_conv.go b/vendor/github.com/nlopes/slack/block_conv.go
new file mode 100644
index 00000000..619867ea
--- /dev/null
+++ b/vendor/github.com/nlopes/slack/block_conv.go
@@ -0,0 +1,303 @@
+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 "section":
+			block = &SectionBlock{}
+		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
+}
+
+// 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 "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/nlopes/slack/block_divider.go b/vendor/github.com/nlopes/slack/block_divider.go
new file mode 100644
index 00000000..2d442ba1
--- /dev/null
+++ b/vendor/github.com/nlopes/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/nlopes/slack/block_element.go b/vendor/github.com/nlopes/slack/block_element.go
new file mode 100644
index 00000000..c62ba99c
--- /dev/null
+++ b/vendor/github.com/nlopes/slack/block_element.go
@@ -0,0 +1,238 @@
+package slack
+
+// https://api.slack.com/reference/messaging/block-elements
+
+const (
+	METImage      MessageElementType = "image"
+	METButton     MessageElementType = "button"
+	METOverflow   MessageElementType = "overflow"
+	METDatepicker MessageElementType = "datepicker"
+
+	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,
+	}
+}
diff --git a/vendor/github.com/nlopes/slack/block_image.go b/vendor/github.com/nlopes/slack/block_image.go
new file mode 100644
index 00000000..6de3f63a
--- /dev/null
+++ b/vendor/github.com/nlopes/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/nlopes/slack/block_object.go b/vendor/github.com/nlopes/slack/block_object.go
new file mode 100644
index 00000000..9e77e6c7
--- /dev/null
+++ b/vendor/github.com/nlopes/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"`
+}
+
+// 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/nlopes/slack/block_section.go b/vendor/github.com/nlopes/slack/block_section.go
new file mode 100644
index 00000000..01ffd5a1
--- /dev/null
+++ b/vendor/github.com/nlopes/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/nlopes/slack/bots.go b/vendor/github.com/nlopes/slack/bots.go
index e27e76ab..5d5a2add 100644
--- a/vendor/github.com/nlopes/slack/bots.go
+++ b/vendor/github.com/nlopes/slack/bots.go
@@ -2,7 +2,6 @@ package slack
 
 import (
 	"context"
-	"errors"
 	"net/url"
 )
 
@@ -19,15 +18,17 @@ type botResponseFull struct {
 	SlackResponse
 }
 
-func botRequest(ctx context.Context, client httpClient, path string, values url.Values, d debug) (*botResponseFull, error) {
+func (api *Client) botRequest(ctx context.Context, path string, values url.Values) (*botResponseFull, error) {
 	response := &botResponseFull{}
-	err := postSlackMethod(ctx, client, path, values, response, d)
+	err := api.postMethod(ctx, path, values, response)
 	if err != nil {
 		return nil, err
 	}
-	if !response.Ok {
-		return nil, errors.New(response.Error)
+
+	if err := response.Err(); err != nil {
+		return nil, err
 	}
+
 	return response, nil
 }
 
@@ -40,10 +41,13 @@ func (api *Client) GetBotInfo(bot string) (*Bot, error) {
 func (api *Client) GetBotInfoContext(ctx context.Context, bot string) (*Bot, error) {
 	values := url.Values{
 		"token": {api.token},
-		"bot":   {bot},
 	}
 
-	response, err := botRequest(ctx, api.httpclient, "bots.info", values, api)
+	if bot != "" {
+		values.Add("bot", bot)
+	}
+
+	response, err := api.botRequest(ctx, "bots.info", values)
 	if err != nil {
 		return nil, err
 	}
diff --git a/vendor/github.com/nlopes/slack/channels.go b/vendor/github.com/nlopes/slack/channels.go
index 711ae7c5..c99e6655 100644
--- a/vendor/github.com/nlopes/slack/channels.go
+++ b/vendor/github.com/nlopes/slack/channels.go
@@ -2,7 +2,6 @@ package slack
 
 import (
 	"context"
-	"errors"
 	"net/url"
 	"strconv"
 )
@@ -19,23 +18,21 @@ type channelResponseFull struct {
 
 // Channel contains information about the channel
 type Channel struct {
-	groupConversation
+	GroupConversation
 	IsChannel bool   `json:"is_channel"`
 	IsGeneral bool   `json:"is_general"`
 	IsMember  bool   `json:"is_member"`
 	Locale    string `json:"locale"`
 }
 
-func channelRequest(ctx context.Context, client httpClient, path string, values url.Values, d debug) (*channelResponseFull, error) {
+func (api *Client) channelRequest(ctx context.Context, path string, values url.Values) (*channelResponseFull, error) {
 	response := &channelResponseFull{}
-	err := postForm(ctx, client, APIURL+path, values, response, d)
+	err := postForm(ctx, api.httpclient, api.endpoint+path, values, response, api)
 	if err != nil {
 		return nil, err
 	}
-	if !response.Ok {
-		return nil, errors.New(response.Error)
-	}
-	return response, nil
+
+	return response, response.Err()
 }
 
 type channelsConfig struct {
@@ -75,7 +72,7 @@ func (api *Client) ArchiveChannelContext(ctx context.Context, channelID string)
 		"channel": {channelID},
 	}
 
-	_, err = channelRequest(ctx, api.httpclient, "channels.archive", values, api)
+	_, err = api.channelRequest(ctx, "channels.archive", values)
 	return err
 }
 
@@ -93,7 +90,7 @@ func (api *Client) UnarchiveChannelContext(ctx context.Context, channelID string
 		"channel": {channelID},
 	}
 
-	_, err = channelRequest(ctx, api.httpclient, "channels.unarchive", values, api)
+	_, err = api.channelRequest(ctx, "channels.unarchive", values)
 	return err
 }
 
@@ -111,7 +108,7 @@ func (api *Client) CreateChannelContext(ctx context.Context, channelName string)
 		"name":  {channelName},
 	}
 
-	response, err := channelRequest(ctx, api.httpclient, "channels.create", values, api)
+	response, err := api.channelRequest(ctx, "channels.create", values)
 	if err != nil {
 		return nil, err
 	}
@@ -156,7 +153,7 @@ func (api *Client) GetChannelHistoryContext(ctx context.Context, channelID strin
 		}
 	}
 
-	response, err := channelRequest(ctx, api.httpclient, "channels.history", values, api)
+	response, err := api.channelRequest(ctx, "channels.history", values)
 	if err != nil {
 		return nil, err
 	}
@@ -178,7 +175,7 @@ func (api *Client) GetChannelInfoContext(ctx context.Context, channelID string)
 		"include_locale": {strconv.FormatBool(true)},
 	}
 
-	response, err := channelRequest(ctx, api.httpclient, "channels.info", values, api)
+	response, err := api.channelRequest(ctx, "channels.info", values)
 	if err != nil {
 		return nil, err
 	}
@@ -200,7 +197,7 @@ func (api *Client) InviteUserToChannelContext(ctx context.Context, channelID, us
 		"user":    {user},
 	}
 
-	response, err := channelRequest(ctx, api.httpclient, "channels.invite", values, api)
+	response, err := api.channelRequest(ctx, "channels.invite", values)
 	if err != nil {
 		return nil, err
 	}
@@ -221,7 +218,7 @@ func (api *Client) JoinChannelContext(ctx context.Context, channelName string) (
 		"name":  {channelName},
 	}
 
-	response, err := channelRequest(ctx, api.httpclient, "channels.join", values, api)
+	response, err := api.channelRequest(ctx, "channels.join", values)
 	if err != nil {
 		return nil, err
 	}
@@ -242,7 +239,7 @@ func (api *Client) LeaveChannelContext(ctx context.Context, channelID string) (b
 		"channel": {channelID},
 	}
 
-	response, err := channelRequest(ctx, api.httpclient, "channels.leave", values, api)
+	response, err := api.channelRequest(ctx, "channels.leave", values)
 	if err != nil {
 		return false, err
 	}
@@ -265,7 +262,7 @@ func (api *Client) KickUserFromChannelContext(ctx context.Context, channelID, us
 		"user":    {user},
 	}
 
-	_, err = channelRequest(ctx, api.httpclient, "channels.kick", values, api)
+	_, err = api.channelRequest(ctx, "channels.kick", values)
 	return err
 }
 
@@ -283,6 +280,7 @@ func (api *Client) GetChannelsContext(ctx context.Context, excludeArchived bool,
 			"token": {api.token},
 		},
 	}
+
 	if excludeArchived {
 		options = append(options, GetChannelsOptionExcludeArchived())
 	}
@@ -293,7 +291,7 @@ func (api *Client) GetChannelsContext(ctx context.Context, excludeArchived bool,
 		}
 	}
 
-	response, err := channelRequest(ctx, api.httpclient, "channels.list", config.values, api)
+	response, err := api.channelRequest(ctx, "channels.list", config.values)
 	if err != nil {
 		return nil, err
 	}
@@ -320,7 +318,7 @@ func (api *Client) SetChannelReadMarkContext(ctx context.Context, channelID, ts
 		"ts":      {ts},
 	}
 
-	_, err = channelRequest(ctx, api.httpclient, "channels.mark", values, api)
+	_, err = api.channelRequest(ctx, "channels.mark", values)
 	return err
 }
 
@@ -341,7 +339,7 @@ func (api *Client) RenameChannelContext(ctx context.Context, channelID, name str
 
 	// 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 := channelRequest(ctx, api.httpclient, "channels.rename", values, api)
+	response, err := api.channelRequest(ctx, "channels.rename", values)
 	if err != nil {
 		return nil, err
 	}
@@ -363,7 +361,7 @@ func (api *Client) SetChannelPurposeContext(ctx context.Context, channelID, purp
 		"purpose": {purpose},
 	}
 
-	response, err := channelRequest(ctx, api.httpclient, "channels.setPurpose", values, api)
+	response, err := api.channelRequest(ctx, "channels.setPurpose", values)
 	if err != nil {
 		return "", err
 	}
@@ -385,7 +383,7 @@ func (api *Client) SetChannelTopicContext(ctx context.Context, channelID, topic
 		"topic":   {topic},
 	}
 
-	response, err := channelRequest(ctx, api.httpclient, "channels.setTopic", values, api)
+	response, err := api.channelRequest(ctx, "channels.setTopic", values)
 	if err != nil {
 		return "", err
 	}
@@ -406,7 +404,7 @@ func (api *Client) GetChannelRepliesContext(ctx context.Context, channelID, thre
 		"channel":   {channelID},
 		"thread_ts": {thread_ts},
 	}
-	response, err := channelRequest(ctx, api.httpclient, "channels.replies", values, api)
+	response, err := api.channelRequest(ctx, "channels.replies", values)
 	if err != nil {
 		return nil, err
 	}
diff --git a/vendor/github.com/nlopes/slack/chat.go b/vendor/github.com/nlopes/slack/chat.go
index c08c1808..a480e5a7 100644
--- a/vendor/github.com/nlopes/slack/chat.go
+++ b/vendor/github.com/nlopes/slack/chat.go
@@ -3,6 +3,7 @@ package slack
 import (
 	"context"
 	"encoding/json"
+	"net/http"
 	"net/url"
 
 	"github.com/nlopes/slack/slackutilsx"
@@ -25,7 +26,7 @@ const (
 
 type chatResponseFull struct {
 	Channel          string `json:"channel"`
-	Timestamp        string `json:"ts"`         //Regualr message timestamp
+	Timestamp        string `json:"ts"`         //Regular message timestamp
 	MessageTimeStamp string `json:"message_ts"` //Ephemeral message timestamp
 	Text             string `json:"text"`
 	SlackResponse
@@ -156,17 +157,18 @@ func (api *Client) SendMessage(channel string, options ...MsgOption) (string, st
 }
 
 // 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) {
+func (api *Client) SendMessageContext(ctx context.Context, channelID string, options ...MsgOption) (_channel string, _timestamp string, _text string, err error) {
 	var (
-		config   sendConfig
+		req      *http.Request
+		parser   func(*chatResponseFull) responseParser
 		response chatResponseFull
 	)
 
-	if config, err = applyMsgOptions(api.token, channelID, options...); err != nil {
+	if req, parser, err = buildSender(api.endpoint, options...).BuildRequest(api.token, channelID); err != nil {
 		return "", "", "", err
 	}
 
-	if err = postForm(ctx, api.httpclient, config.endpoint, config.values, &response, api); err != nil {
+	if err = doPost(ctx, api.httpclient, req, parser(&response), api); err != nil {
 		return "", "", "", err
 	}
 
@@ -176,14 +178,15 @@ func (api *Client) SendMessageContext(ctx context.Context, channelID string, opt
 // 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 string, options ...MsgOption) (string, url.Values, error) {
-	config, err := applyMsgOptions(token, channel, options...)
+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 string, options ...MsgOption) (sendConfig, error) {
+func applyMsgOptions(token, channel, apiurl string, options ...MsgOption) (sendConfig, error) {
 	config := sendConfig{
-		endpoint: APIURL + string(chatPostMessage),
+		apiurl:   apiurl,
+		endpoint: apiurl + string(chatPostMessage),
 		values: url.Values{
 			"token":   {token},
 			"channel": {channel},
@@ -199,6 +202,13 @@ func applyMsgOptions(token, channel string, options ...MsgOption) (sendConfig, e
 	return config, nil
 }
 
+func buildSender(apiurl string, options ...MsgOption) sendConfig {
+	return sendConfig{
+		apiurl:  apiurl,
+		options: options,
+	}
+}
+
 type sendMode string
 
 const (
@@ -206,22 +216,77 @@ const (
 	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
+	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,
+			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
+	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,
+		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 = APIURL + string(chatPostMessage)
+		config.endpoint = config.apiurl + string(chatPostMessage)
 		config.values.Del("ts")
 		return nil
 	}
@@ -230,7 +295,7 @@ func MsgOptionPost() MsgOption {
 // MsgOptionPostEphemeral - posts an ephemeral message to the provided user.
 func MsgOptionPostEphemeral(userID string) MsgOption {
 	return func(config *sendConfig) error {
-		config.endpoint = APIURL + string(chatPostEphemeral)
+		config.endpoint = config.apiurl + string(chatPostEphemeral)
 		MsgOptionUser(userID)(config)
 		config.values.Del("ts")
 
@@ -241,7 +306,7 @@ func MsgOptionPostEphemeral(userID string) MsgOption {
 // MsgOptionMeMessage posts a "me message" type from the calling user
 func MsgOptionMeMessage() MsgOption {
 	return func(config *sendConfig) error {
-		config.endpoint = APIURL + string(chatMeMessage)
+		config.endpoint = config.apiurl + string(chatMeMessage)
 		return nil
 	}
 }
@@ -249,7 +314,7 @@ func MsgOptionMeMessage() MsgOption {
 // MsgOptionUpdate updates a message based on the timestamp.
 func MsgOptionUpdate(timestamp string) MsgOption {
 	return func(config *sendConfig) error {
-		config.endpoint = APIURL + string(chatUpdate)
+		config.endpoint = config.apiurl + string(chatUpdate)
 		config.values.Add("ts", timestamp)
 		return nil
 	}
@@ -258,7 +323,7 @@ func MsgOptionUpdate(timestamp string) MsgOption {
 // MsgOptionDelete deletes a message based on the timestamp.
 func MsgOptionDelete(timestamp string) MsgOption {
 	return func(config *sendConfig) error {
-		config.endpoint = APIURL + string(chatDelete)
+		config.endpoint = config.apiurl + string(chatDelete)
 		config.values.Add("ts", timestamp)
 		return nil
 	}
@@ -267,7 +332,7 @@ func MsgOptionDelete(timestamp string) MsgOption {
 // MsgOptionUnfurl unfurls a message based on the timestamp.
 func MsgOptionUnfurl(timestamp string, unfurls map[string]Attachment) MsgOption {
 	return func(config *sendConfig) error {
-		config.endpoint = APIURL + string(chatUnfurl)
+		config.endpoint = config.apiurl + string(chatUnfurl)
 		config.values.Add("ts", timestamp)
 		unfurlsStr, err := json.Marshal(unfurls)
 		if err == nil {
@@ -277,6 +342,17 @@ func MsgOptionUnfurl(timestamp string, unfurls map[string]Attachment) MsgOption
 	}
 }
 
+// MsgOptionResponseURL supplies a url to use as the endpoint.
+func MsgOptionResponseURL(url string, rt string) MsgOption {
+	return func(config *sendConfig) error {
+		config.mode = chatResponse
+		config.endpoint = url
+		config.responseType = rt
+		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 {
@@ -322,9 +398,31 @@ func MsgOptionAttachments(attachments ...Attachment) MsgOption {
 			return nil
 		}
 
-		attachments, err := json.Marshal(attachments)
+		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(attachments))
+			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
+		}
+
+		blocks, err := json.Marshal(blocks)
+		if err == nil {
+			config.values.Set("blocks", string(blocks))
 		}
 		return err
 	}
@@ -395,15 +493,31 @@ func MsgOptionParse(b bool) MsgOption {
 	return func(c *sendConfig) error {
 		var v string
 		if b {
-			v = "1"
+			v = "full"
 		} else {
-			v = "0"
+			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
@@ -499,7 +613,7 @@ func (api *Client) GetPermalinkContext(ctx context.Context, params *PermalinkPar
 		Permalink string `json:"permalink"`
 		SlackResponse
 	}{}
-	err := getSlackMethod(ctx, api.httpclient, "chat.getPermalink", values, &response, api)
+	err := api.getMethod(ctx, "chat.getPermalink", values, &response)
 	if err != nil {
 		return "", err
 	}
diff --git a/vendor/github.com/nlopes/slack/conversation.go b/vendor/github.com/nlopes/slack/conversation.go
index ccd38f88..1e4a61f1 100644
--- a/vendor/github.com/nlopes/slack/conversation.go
+++ b/vendor/github.com/nlopes/slack/conversation.go
@@ -2,14 +2,13 @@ package slack
 
 import (
 	"context"
-	"errors"
 	"net/url"
 	"strconv"
 	"strings"
 )
 
 // Conversation is the foundation for IM and BaseGroupConversation
-type conversation struct {
+type Conversation struct {
 	ID                 string   `json:"id"`
 	Created            JSONTime `json:"created"`
 	IsOpen             bool     `json:"is_open"`
@@ -36,8 +35,8 @@ type conversation struct {
 }
 
 // GroupConversation is the foundation for Group and Channel
-type groupConversation struct {
-	conversation
+type GroupConversation struct {
+	Conversation
 	Name       string   `json:"name"`
 	Creator    string   `json:"creator"`
 	IsArchived bool     `json:"is_archived"`
@@ -67,10 +66,11 @@ type GetUsersInConversationParameters struct {
 }
 
 type GetConversationsForUserParameters struct {
-	UserID string
-	Cursor string
-	Types  []string
-	Limit  int
+	UserID          string
+	Cursor          string
+	Types           []string
+	Limit           int
+	ExcludeArchived bool
 }
 
 type responseMetaData struct {
@@ -99,13 +99,16 @@ func (api *Client) GetUsersInConversationContext(ctx context.Context, params *Ge
 		ResponseMetaData responseMetaData `json:"response_metadata"`
 		SlackResponse
 	}{}
-	err := postSlackMethod(ctx, api.httpclient, "conversations.members", values, &response, api)
+
+	err := api.postMethod(ctx, "conversations.members", values, &response)
 	if err != nil {
 		return nil, "", err
 	}
-	if !response.Ok {
-		return nil, "", errors.New(response.Error)
+
+	if err := response.Err(); err != nil {
+		return nil, "", err
 	}
+
 	return response.Members, response.ResponseMetaData.NextCursor, nil
 }
 
@@ -131,12 +134,15 @@ func (api *Client) GetConversationsForUserContext(ctx context.Context, params *G
 	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 = postSlackMethod(ctx, api.httpclient, "users.conversations", values, &response, api)
+	err = api.postMethod(ctx, "users.conversations", values, &response)
 	if err != nil {
 		return nil, "", err
 	}
@@ -155,8 +161,9 @@ func (api *Client) ArchiveConversationContext(ctx context.Context, channelID str
 		"token":   {api.token},
 		"channel": {channelID},
 	}
+
 	response := SlackResponse{}
-	err := postSlackMethod(ctx, api.httpclient, "conversations.archive", values, &response, api)
+	err := api.postMethod(ctx, "conversations.archive", values, &response)
 	if err != nil {
 		return err
 	}
@@ -176,7 +183,7 @@ func (api *Client) UnArchiveConversationContext(ctx context.Context, channelID s
 		"channel": {channelID},
 	}
 	response := SlackResponse{}
-	err := postSlackMethod(ctx, api.httpclient, "conversations.unarchive", values, &response, api)
+	err := api.postMethod(ctx, "conversations.unarchive", values, &response)
 	if err != nil {
 		return err
 	}
@@ -200,7 +207,7 @@ func (api *Client) SetTopicOfConversationContext(ctx context.Context, channelID,
 		SlackResponse
 		Channel *Channel `json:"channel"`
 	}{}
-	err := postSlackMethod(ctx, api.httpclient, "conversations.setTopic", values, &response, api)
+	err := api.postMethod(ctx, "conversations.setTopic", values, &response)
 	if err != nil {
 		return nil, err
 	}
@@ -224,7 +231,8 @@ func (api *Client) SetPurposeOfConversationContext(ctx context.Context, channelI
 		SlackResponse
 		Channel *Channel `json:"channel"`
 	}{}
-	err := postSlackMethod(ctx, api.httpclient, "conversations.setPurpose", values, &response, api)
+
+	err := api.postMethod(ctx, "conversations.setPurpose", values, &response)
 	if err != nil {
 		return nil, err
 	}
@@ -248,7 +256,8 @@ func (api *Client) RenameConversationContext(ctx context.Context, channelID, cha
 		SlackResponse
 		Channel *Channel `json:"channel"`
 	}{}
-	err := postSlackMethod(ctx, api.httpclient, "conversations.rename", values, &response, api)
+
+	err := api.postMethod(ctx, "conversations.rename", values, &response)
 	if err != nil {
 		return nil, err
 	}
@@ -272,7 +281,8 @@ func (api *Client) InviteUsersToConversationContext(ctx context.Context, channel
 		SlackResponse
 		Channel *Channel `json:"channel"`
 	}{}
-	err := postSlackMethod(ctx, api.httpclient, "conversations.invite", values, &response, api)
+
+	err := api.postMethod(ctx, "conversations.invite", values, &response)
 	if err != nil {
 		return nil, err
 	}
@@ -292,8 +302,9 @@ func (api *Client) KickUserFromConversationContext(ctx context.Context, channelI
 		"channel": {channelID},
 		"user":    {user},
 	}
+
 	response := SlackResponse{}
-	err := postSlackMethod(ctx, api.httpclient, "conversations.kick", values, &response, api)
+	err := api.postMethod(ctx, "conversations.kick", values, &response)
 	if err != nil {
 		return err
 	}
@@ -318,7 +329,7 @@ func (api *Client) CloseConversationContext(ctx context.Context, channelID strin
 		AlreadyClosed bool `json:"already_closed"`
 	}{}
 
-	err = postSlackMethod(ctx, api.httpclient, "conversations.close", values, &response, api)
+	err = api.postMethod(ctx, "conversations.close", values, &response)
 	if err != nil {
 		return false, false, err
 	}
@@ -338,13 +349,12 @@ func (api *Client) CreateConversationContext(ctx context.Context, channelName st
 		"name":       {channelName},
 		"is_private": {strconv.FormatBool(isPrivate)},
 	}
-	response, err := channelRequest(
-		ctx, api.httpclient, "conversations.create", values, api)
+	response, err := api.channelRequest(ctx, "conversations.create", values)
 	if err != nil {
 		return nil, err
 	}
 
-	return &response.Channel, response.Err()
+	return &response.Channel, nil
 }
 
 // GetConversationInfo retrieves information about a conversation
@@ -359,8 +369,7 @@ func (api *Client) GetConversationInfoContext(ctx context.Context, channelID str
 		"channel":        {channelID},
 		"include_locale": {strconv.FormatBool(includeLocale)},
 	}
-	response, err := channelRequest(
-		ctx, api.httpclient, "conversations.info", values, api)
+	response, err := api.channelRequest(ctx, "conversations.info", values)
 	if err != nil {
 		return nil, err
 	}
@@ -380,7 +389,7 @@ func (api *Client) LeaveConversationContext(ctx context.Context, channelID strin
 		"channel": {channelID},
 	}
 
-	response, err := channelRequest(ctx, api.httpclient, "conversations.leave", values, api)
+	response, err := api.channelRequest(ctx, "conversations.leave", values)
 	if err != nil {
 		return false, err
 	}
@@ -436,7 +445,7 @@ func (api *Client) GetConversationRepliesContext(ctx context.Context, params *Ge
 		Messages []Message `json:"messages"`
 	}{}
 
-	err = postSlackMethod(ctx, api.httpclient, "conversations.replies", values, &response, api)
+	err = api.postMethod(ctx, "conversations.replies", values, &response)
 	if err != nil {
 		return nil, false, "", err
 	}
@@ -476,7 +485,8 @@ func (api *Client) GetConversationsContext(ctx context.Context, params *GetConve
 		ResponseMetaData responseMetaData `json:"response_metadata"`
 		SlackResponse
 	}{}
-	err = postSlackMethod(ctx, api.httpclient, "conversations.list", values, &response, api)
+
+	err = api.postMethod(ctx, "conversations.list", values, &response)
 	if err != nil {
 		return nil, "", err
 	}
@@ -513,7 +523,8 @@ func (api *Client) OpenConversationContext(ctx context.Context, params *OpenConv
 		AlreadyOpen bool     `json:"already_open"`
 		SlackResponse
 	}{}
-	err := postSlackMethod(ctx, api.httpclient, "conversations.open", values, &response, api)
+
+	err := api.postMethod(ctx, "conversations.open", values, &response)
 	if err != nil {
 		return nil, false, false, err
 	}
@@ -537,7 +548,8 @@ func (api *Client) JoinConversationContext(ctx context.Context, channelID string
 		} `json:"response_metadata"`
 		SlackResponse
 	}{}
-	err := postSlackMethod(ctx, api.httpclient, "conversations.join", values, &response, api)
+
+	err := api.postMethod(ctx, "conversations.join", values, &response)
 	if err != nil {
 		return nil, "", nil, err
 	}
@@ -599,7 +611,7 @@ func (api *Client) GetConversationHistoryContext(ctx context.Context, params *Ge
 
 	response := GetConversationHistoryResponse{}
 
-	err := postSlackMethod(ctx, api.httpclient, "conversations.history", values, &response, api)
+	err := api.postMethod(ctx, "conversations.history", values, &response)
 	if err != nil {
 		return nil, err
 	}
diff --git a/vendor/github.com/nlopes/slack/dialog.go b/vendor/github.com/nlopes/slack/dialog.go
index 7b9e3814..376cd9e6 100644
--- a/vendor/github.com/nlopes/slack/dialog.go
+++ b/vendor/github.com/nlopes/slack/dialog.go
@@ -3,7 +3,7 @@ package slack
 import (
 	"context"
 	"encoding/json"
-	"errors"
+	"strings"
 )
 
 // InputType is the type of the dialog input type
@@ -25,6 +25,7 @@ type DialogInput struct {
 	Name        string    `json:"name"`
 	Placeholder string    `json:"placeholder"`
 	Optional    bool      `json:"optional"`
+	Hint        string    `json:"hint"`
 }
 
 // DialogTrigger ...
@@ -89,7 +90,7 @@ func (api *Client) OpenDialog(triggerID string, dialog Dialog) (err error) {
 // 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 errors.New("received empty parameters")
+		return ErrParametersMissing
 	}
 
 	req := DialogTrigger{
@@ -103,10 +104,15 @@ func (api *Client) OpenDialogContext(ctx context.Context, triggerID string, dial
 	}
 
 	response := &DialogOpenResponse{}
-	endpoint := APIURL + "dialog.open"
+	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/nlopes/slack/dialog_select.go b/vendor/github.com/nlopes/slack/dialog_select.go
index ea95ccfa..385cef68 100644
--- a/vendor/github.com/nlopes/slack/dialog_select.go
+++ b/vendor/github.com/nlopes/slack/dialog_select.go
@@ -21,10 +21,11 @@ type DialogInputSelect struct {
 	DialogInput
 	Value           string               `json:"value,omitempty"`            //Optional.
 	DataSource      SelectDataSource     `json:"data_source,omitempty"`      //Optional. Allowed values: "users", "channels", "conversations", "external".
-	SelectedOptions string               `json:"selected_options,omitempty"` //Optional. Default value for "external" only
+	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
@@ -54,14 +55,7 @@ func NewStaticSelectDialogInput(name, label string, options []DialogSelectOption
 }
 
 // NewGroupedSelectDialogInput creates grouped options select input for Dialogs.
-func NewGroupedSelectDialogInput(name, label string, groups map[string]map[string]string) *DialogInputSelect {
-	optionGroups := []DialogOptionGroup{}
-	for groupName, options := range groups {
-		optionGroups = append(optionGroups, DialogOptionGroup{
-			Label:   groupName,
-			Options: optionsFromMap(options),
-		})
-	}
+func NewGroupedSelectDialogInput(name, label string, options []DialogOptionGroup) *DialogInputSelect {
 	return &DialogInputSelect{
 		DialogInput: DialogInput{
 			Type:  InputTypeSelect,
@@ -69,34 +63,15 @@ func NewGroupedSelectDialogInput(name, label string, groups map[string]map[strin
 			Label: label,
 		},
 		DataSource:   DialogDataSourceStatic,
-		OptionGroups: optionGroups,
-	}
-}
-
-func optionsFromArray(options []string) []DialogSelectOption {
-	selectOptions := make([]DialogSelectOption, len(options))
-	for idx, value := range options {
-		selectOptions[idx] = DialogSelectOption{
-			Label: value,
-			Value: value,
-		}
-	}
-	return selectOptions
+		OptionGroups: options}
 }
 
-func optionsFromMap(options map[string]string) []DialogSelectOption {
-	selectOptions := make([]DialogSelectOption, len(options))
-	idx := 0
-	var option DialogSelectOption
-	for key, value := range options {
-		option = DialogSelectOption{
-			Label: key,
-			Value: value,
-		}
-		selectOptions[idx] = option
-		idx++
+// NewDialogOptionGroup creates a DialogOptionGroup from several select options
+func NewDialogOptionGroup(label string, options ...DialogSelectOption) DialogOptionGroup {
+	return DialogOptionGroup{
+		Label:   label,
+		Options: options,
 	}
-	return selectOptions
 }
 
 // NewConversationsSelect returns a `Conversations` select
diff --git a/vendor/github.com/nlopes/slack/dialog_text.go b/vendor/github.com/nlopes/slack/dialog_text.go
index bf9602cc..da06bd6d 100644
--- a/vendor/github.com/nlopes/slack/dialog_text.go
+++ b/vendor/github.com/nlopes/slack/dialog_text.go
@@ -3,6 +3,9 @@ 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"
@@ -26,8 +29,8 @@ type TextInputElement struct {
 }
 
 // NewTextInput constructor for a `text` input
-func NewTextInput(name, label, text string) *TextInputElement {
-	return &TextInputElement{
+func NewTextInput(name, label, text string, options ...TextInputOption) *TextInputElement {
+	t := &TextInputElement{
 		DialogInput: DialogInput{
 			Type:  InputTypeText,
 			Name:  name,
@@ -35,6 +38,12 @@ func NewTextInput(name, label, text string) *TextInputElement {
 		},
 		Value: text,
 	}
+
+	for _, opt := range options {
+		opt(t)
+	}
+
+	return t
 }
 
 // NewTextAreaInput constructor for a `textarea` input
diff --git a/vendor/github.com/nlopes/slack/dnd.go b/vendor/github.com/nlopes/slack/dnd.go
index da6e4a16..a3aa680c 100644
--- a/vendor/github.com/nlopes/slack/dnd.go
+++ b/vendor/github.com/nlopes/slack/dnd.go
@@ -2,7 +2,6 @@ package slack
 
 import (
 	"context"
-	"errors"
 	"net/url"
 	"strconv"
 	"strings"
@@ -36,16 +35,14 @@ type dndTeamInfoResponse struct {
 	SlackResponse
 }
 
-func dndRequest(ctx context.Context, client httpClient, path string, values url.Values, d debug) (*dndResponseFull, error) {
+func (api *Client) dndRequest(ctx context.Context, path string, values url.Values) (*dndResponseFull, error) {
 	response := &dndResponseFull{}
-	err := postSlackMethod(ctx, client, path, values, response, d)
+	err := api.postMethod(ctx, path, values, response)
 	if err != nil {
 		return nil, err
 	}
-	if !response.Ok {
-		return nil, errors.New(response.Error)
-	}
-	return response, nil
+
+	return response, response.Err()
 }
 
 // EndDND ends the user's scheduled Do Not Disturb session
@@ -61,7 +58,7 @@ func (api *Client) EndDNDContext(ctx context.Context) error {
 
 	response := &SlackResponse{}
 
-	if err := postSlackMethod(ctx, api.httpclient, "dnd.endDnd", values, response, api); err != nil {
+	if err := api.postMethod(ctx, "dnd.endDnd", values, response); err != nil {
 		return err
 	}
 
@@ -79,7 +76,7 @@ func (api *Client) EndSnoozeContext(ctx context.Context) (*DNDStatus, error) {
 		"token": {api.token},
 	}
 
-	response, err := dndRequest(ctx, api.httpclient, "dnd.endSnooze", values, api)
+	response, err := api.dndRequest(ctx, "dnd.endSnooze", values)
 	if err != nil {
 		return nil, err
 	}
@@ -100,7 +97,7 @@ func (api *Client) GetDNDInfoContext(ctx context.Context, user *string) (*DNDSta
 		values.Set("user", *user)
 	}
 
-	response, err := dndRequest(ctx, api.httpclient, "dnd.info", values, api)
+	response, err := api.dndRequest(ctx, "dnd.info", values)
 	if err != nil {
 		return nil, err
 	}
@@ -120,13 +117,14 @@ func (api *Client) GetDNDTeamInfoContext(ctx context.Context, users []string) (m
 	}
 	response := &dndTeamInfoResponse{}
 
-	if err := postSlackMethod(ctx, api.httpclient, "dnd.teamInfo", values, response, api); err != nil {
+	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
 }
 
@@ -137,7 +135,7 @@ func (api *Client) SetSnooze(minutes int) (*DNDStatus, error) {
 	return api.SetSnoozeContext(context.Background(), minutes)
 }
 
-// SetSnooze adjusts the snooze duration for a user's Do Not Disturb settings with a custom context.
+// 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{
@@ -145,7 +143,7 @@ func (api *Client) SetSnoozeContext(ctx context.Context, minutes int) (*DNDStatu
 		"num_minutes": {strconv.Itoa(minutes)},
 	}
 
-	response, err := dndRequest(ctx, api.httpclient, "dnd.setSnooze", values, api)
+	response, err := api.dndRequest(ctx, "dnd.setSnooze", values)
 	if err != nil {
 		return nil, err
 	}
diff --git a/vendor/github.com/nlopes/slack/emoji.go b/vendor/github.com/nlopes/slack/emoji.go
index aed2129f..b2b0c6c9 100644
--- a/vendor/github.com/nlopes/slack/emoji.go
+++ b/vendor/github.com/nlopes/slack/emoji.go
@@ -2,7 +2,6 @@ package slack
 
 import (
 	"context"
-	"errors"
 	"net/url"
 )
 
@@ -23,12 +22,14 @@ func (api *Client) GetEmojiContext(ctx context.Context) (map[string]string, erro
 	}
 	response := &emojiResponseFull{}
 
-	err := postSlackMethod(ctx, api.httpclient, "emoji.list", values, response, api)
+	err := api.postMethod(ctx, "emoji.list", values, response)
 	if err != nil {
 		return nil, err
 	}
-	if !response.Ok {
-		return nil, errors.New(response.Error)
+
+	if response.Err() != nil {
+		return nil, response.Err()
 	}
+
 	return response.Emoji, nil
 }
diff --git a/vendor/github.com/nlopes/slack/errors.go b/vendor/github.com/nlopes/slack/errors.go
new file mode 100644
index 00000000..09113ff1
--- /dev/null
+++ b/vendor/github.com/nlopes/slack/errors.go
@@ -0,0 +1,18 @@
+package slack
+
+import "github.com/nlopes/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")
+	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/nlopes/slack/files.go b/vendor/github.com/nlopes/slack/files.go
index 136ea266..3a7363de 100644
--- a/vendor/github.com/nlopes/slack/files.go
+++ b/vendor/github.com/nlopes/slack/files.go
@@ -2,7 +2,6 @@ package slack
 
 import (
 	"context"
-	"errors"
 	"fmt"
 	"io"
 	"net/url"
@@ -91,7 +90,8 @@ type File struct {
 }
 
 type Share struct {
-	Public map[string][]ShareFileInfo `json:"public"`
+	Public  map[string][]ShareFileInfo `json:"public"`
+	Private map[string][]ShareFileInfo `json:"private"`
 }
 
 type ShareFileInfo struct {
@@ -134,11 +134,21 @@ type GetFilesParameters struct {
 	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"`
+	Comments []Comment        `json:"comments"`
+	Files    []File           `json:"files"`
+	Metadata ResponseMetadata `json:"response_metadata"`
 
 	SlackResponse
 }
@@ -156,9 +166,9 @@ func NewGetFilesParameters() GetFilesParameters {
 	}
 }
 
-func fileRequest(ctx context.Context, client httpClient, path string, values url.Values, d debug) (*fileResponseFull, error) {
+func (api *Client) fileRequest(ctx context.Context, path string, values url.Values) (*fileResponseFull, error) {
 	response := &fileResponseFull{}
-	err := postForm(ctx, client, APIURL+path, values, response, d)
+	err := api.postMethod(ctx, path, values, response)
 	if err != nil {
 		return nil, err
 	}
@@ -180,18 +190,57 @@ func (api *Client) GetFileInfoContext(ctx context.Context, fileID string, count,
 		"page":  {strconv.Itoa(page)},
 	}
 
-	response, err := fileRequest(ctx, api.httpclient, "files.info", values, api)
+	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{
@@ -219,7 +268,7 @@ func (api *Client) GetFilesContext(ctx context.Context, params GetFilesParameter
 		values.Add("page", strconv.Itoa(params.Page))
 	}
 
-	response, err := fileRequest(ctx, api.httpclient, "files.list", values, api)
+	response, err := api.fileRequest(ctx, "files.list", values)
 	if err != nil {
 		return nil, nil, err
 	}
@@ -239,9 +288,6 @@ func (api *Client) UploadFileContext(ctx context.Context, params FileUploadParam
 	if err != nil {
 		return nil, err
 	}
-	if params.Filename == "" {
-		return nil, fmt.Errorf("files.upload: FileUploadParameters.Filename is mandatory")
-	}
 	response := &fileResponseFull{}
 	values := url.Values{
 		"token": {api.token},
@@ -266,12 +312,16 @@ func (api *Client) UploadFileContext(ctx context.Context, params FileUploadParam
 	}
 	if params.Content != "" {
 		values.Add("content", params.Content)
-		err = postForm(ctx, api.httpclient, APIURL+"files.upload", values, response, api)
+		err = api.postMethod(ctx, "files.upload", values, response)
 	} else if params.File != "" {
-		err = postLocalWithMultipartResponse(ctx, api.httpclient, "files.upload", params.File, "file", values, response, api)
+		err = postLocalWithMultipartResponse(ctx, api.httpclient, api.endpoint+"files.upload", params.File, "file", values, response, api)
 	} else if params.Reader != nil {
-		err = postWithMultipartResponse(ctx, api.httpclient, "files.upload", params.Filename, "file", values, params.Reader, response, api)
+		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
 	}
@@ -287,7 +337,7 @@ func (api *Client) DeleteFileComment(commentID, fileID string) error {
 // 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 errors.New("received empty parameters")
+		return ErrParametersMissing
 	}
 
 	values := url.Values{
@@ -295,7 +345,7 @@ func (api *Client) DeleteFileCommentContext(ctx context.Context, fileID, comment
 		"file":  {fileID},
 		"id":    {commentID},
 	}
-	_, err = fileRequest(ctx, api.httpclient, "files.comments.delete", values, api)
+	_, err = api.fileRequest(ctx, "files.comments.delete", values)
 	return err
 }
 
@@ -311,7 +361,7 @@ func (api *Client) DeleteFileContext(ctx context.Context, fileID string) (err er
 		"file":  {fileID},
 	}
 
-	_, err = fileRequest(ctx, api.httpclient, "files.delete", values, api)
+	_, err = api.fileRequest(ctx, "files.delete", values)
 	return err
 }
 
@@ -327,7 +377,7 @@ func (api *Client) RevokeFilePublicURLContext(ctx context.Context, fileID string
 		"file":  {fileID},
 	}
 
-	response, err := fileRequest(ctx, api.httpclient, "files.revokePublicURL", values, api)
+	response, err := api.fileRequest(ctx, "files.revokePublicURL", values)
 	if err != nil {
 		return nil, err
 	}
@@ -346,7 +396,7 @@ func (api *Client) ShareFilePublicURLContext(ctx context.Context, fileID string)
 		"file":  {fileID},
 	}
 
-	response, err := fileRequest(ctx, api.httpclient, "files.sharedPublicURL", values, api)
+	response, err := api.fileRequest(ctx, "files.sharedPublicURL", values)
 	if err != nil {
 		return nil, nil, nil, err
 	}
diff --git a/vendor/github.com/nlopes/slack/go.mod b/vendor/github.com/nlopes/slack/go.mod
new file mode 100644
index 00000000..87256eb1
--- /dev/null
+++ b/vendor/github.com/nlopes/slack/go.mod
@@ -0,0 +1,9 @@
+module github.com/nlopes/slack
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	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/nlopes/slack/go.sum b/vendor/github.com/nlopes/slack/go.sum
new file mode 100644
index 00000000..3bb45c1f
--- /dev/null
+++ b/vendor/github.com/nlopes/slack/go.sum
@@ -0,0 +1,22 @@
+github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+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/gorilla/websocket v1.2.0 h1:VJtLvh6VQym50czpZzx07z/kw9EgAxI3x1ZB8taTMQQ=
+github.com/gorilla/websocket v1.2.0/go.mod h1:E7qHFY5m1UJ88s3WnNqhKjPHQ0heANvMoAMk2YaljkQ=
+github.com/nlopes/slack v0.1.0/go.mod h1:jVI4BBK3lSktibKahxBF74txcK2vyvkza1z/+rRnVAM=
+github.com/nlopes/slack v0.5.0 h1:NbIae8Kd0NpqaEI3iUrsuS0KbcEDhzhc939jLW5fNm0=
+github.com/nlopes/slack v0.5.0/go.mod h1:jVI4BBK3lSktibKahxBF74txcK2vyvkza1z/+rRnVAM=
+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 v1.2.0/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
+github.com/stretchr/testify v1.2.2 h1:bSDNvY7ZPG5RlJ8otE/7V6gMiyenm9RtJ7IUVIAoJ1w=
+github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
+github.com/victorcoder/slack-test v0.0.0-20190131110821-6f9a569c10af h1:JFxr+No3ZWgCtxnnTWCybnB/z0Iy3qLmdj3u2NV5o48=
+github.com/victorcoder/slack-test v0.0.0-20190131110821-6f9a569c10af/go.mod h1:dStM4ShMus8J3hiq66ExbbzGLkwyZ+RQJePwFhWCCvQ=
+github.com/victorcoder/slack-test v0.0.0-20190131113129-a43b3bb77f43 h1:wtFekkaAAQibpy3iE4Hhx2Gi9pZAbITOSfVP7GXk5eM=
+github.com/victorcoder/slack-test v0.0.0-20190131113129-a43b3bb77f43/go.mod h1:dStM4ShMus8J3hiq66ExbbzGLkwyZ+RQJePwFhWCCvQ=
+golang.org/x/net v0.0.0-20180108090419-434ec0c7fe37 h1:BkNcmLtAVeWe9h5k0jt24CQgaG5vb4x/doFbAiEC/Ho=
+golang.org/x/net v0.0.0-20180108090419-434ec0c7fe37/go.mod h1:mL1N/T3taQHkDXs73rZJwtUhF3w3ftmwwsq0BUmARs4=
diff --git a/vendor/github.com/nlopes/slack/groups.go b/vendor/github.com/nlopes/slack/groups.go
index 560faee9..23374869 100644
--- a/vendor/github.com/nlopes/slack/groups.go
+++ b/vendor/github.com/nlopes/slack/groups.go
@@ -8,7 +8,7 @@ import (
 
 // Group contains all the information for a group
 type Group struct {
-	groupConversation
+	GroupConversation
 	IsGroup bool `json:"is_group"`
 }
 
@@ -27,9 +27,9 @@ type groupResponseFull struct {
 	SlackResponse
 }
 
-func groupRequest(ctx context.Context, client httpClient, path string, values url.Values, d debug) (*groupResponseFull, error) {
+func (api *Client) groupRequest(ctx context.Context, path string, values url.Values) (*groupResponseFull, error) {
 	response := &groupResponseFull{}
-	err := postForm(ctx, client, APIURL+path, values, response, d)
+	err := api.postMethod(ctx, path, values, response)
 	if err != nil {
 		return nil, err
 	}
@@ -49,7 +49,7 @@ func (api *Client) ArchiveGroupContext(ctx context.Context, group string) error
 		"channel": {group},
 	}
 
-	_, err := groupRequest(ctx, api.httpclient, "groups.archive", values, api)
+	_, err := api.groupRequest(ctx, "groups.archive", values)
 	return err
 }
 
@@ -65,7 +65,7 @@ func (api *Client) UnarchiveGroupContext(ctx context.Context, group string) erro
 		"channel": {group},
 	}
 
-	_, err := groupRequest(ctx, api.httpclient, "groups.unarchive", values, api)
+	_, err := api.groupRequest(ctx, "groups.unarchive", values)
 	return err
 }
 
@@ -81,7 +81,7 @@ func (api *Client) CreateGroupContext(ctx context.Context, group string) (*Group
 		"name":  {group},
 	}
 
-	response, err := groupRequest(ctx, api.httpclient, "groups.create", values, api)
+	response, err := api.groupRequest(ctx, "groups.create", values)
 	if err != nil {
 		return nil, err
 	}
@@ -106,7 +106,7 @@ func (api *Client) CreateChildGroupContext(ctx context.Context, group string) (*
 		"channel": {group},
 	}
 
-	response, err := groupRequest(ctx, api.httpclient, "groups.createChild", values, api)
+	response, err := api.groupRequest(ctx, "groups.createChild", values)
 	if err != nil {
 		return nil, err
 	}
@@ -148,7 +148,7 @@ func (api *Client) GetGroupHistoryContext(ctx context.Context, group string, par
 		}
 	}
 
-	response, err := groupRequest(ctx, api.httpclient, "groups.history", values, api)
+	response, err := api.groupRequest(ctx, "groups.history", values)
 	if err != nil {
 		return nil, err
 	}
@@ -168,7 +168,7 @@ func (api *Client) InviteUserToGroupContext(ctx context.Context, group, user str
 		"user":    {user},
 	}
 
-	response, err := groupRequest(ctx, api.httpclient, "groups.invite", values, api)
+	response, err := api.groupRequest(ctx, "groups.invite", values)
 	if err != nil {
 		return nil, false, err
 	}
@@ -187,7 +187,7 @@ func (api *Client) LeaveGroupContext(ctx context.Context, group string) (err err
 		"channel": {group},
 	}
 
-	_, err = groupRequest(ctx, api.httpclient, "groups.leave", values, api)
+	_, err = api.groupRequest(ctx, "groups.leave", values)
 	return err
 }
 
@@ -204,7 +204,7 @@ func (api *Client) KickUserFromGroupContext(ctx context.Context, group, user str
 		"user":    {user},
 	}
 
-	_, err = groupRequest(ctx, api.httpclient, "groups.kick", values, api)
+	_, err = api.groupRequest(ctx, "groups.kick", values)
 	return err
 }
 
@@ -222,7 +222,7 @@ func (api *Client) GetGroupsContext(ctx context.Context, excludeArchived bool) (
 		values.Add("exclude_archived", "1")
 	}
 
-	response, err := groupRequest(ctx, api.httpclient, "groups.list", values, api)
+	response, err := api.groupRequest(ctx, "groups.list", values)
 	if err != nil {
 		return nil, err
 	}
@@ -242,7 +242,7 @@ func (api *Client) GetGroupInfoContext(ctx context.Context, group string) (*Grou
 		"include_locale": {strconv.FormatBool(true)},
 	}
 
-	response, err := groupRequest(ctx, api.httpclient, "groups.info", values, api)
+	response, err := api.groupRequest(ctx, "groups.info", values)
 	if err != nil {
 		return nil, err
 	}
@@ -267,7 +267,7 @@ func (api *Client) SetGroupReadMarkContext(ctx context.Context, group, ts string
 		"ts":      {ts},
 	}
 
-	_, err = groupRequest(ctx, api.httpclient, "groups.mark", values, api)
+	_, err = api.groupRequest(ctx, "groups.mark", values)
 	return err
 }
 
@@ -283,7 +283,7 @@ func (api *Client) OpenGroupContext(ctx context.Context, group string) (bool, bo
 		"channel": {group},
 	}
 
-	response, err := groupRequest(ctx, api.httpclient, "groups.open", values, api)
+	response, err := api.groupRequest(ctx, "groups.open", values)
 	if err != nil {
 		return false, false, err
 	}
@@ -307,7 +307,7 @@ func (api *Client) RenameGroupContext(ctx context.Context, group, name string) (
 
 	// 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 := groupRequest(ctx, api.httpclient, "groups.rename", values, api)
+	response, err := api.groupRequest(ctx, "groups.rename", values)
 	if err != nil {
 		return nil, err
 	}
@@ -327,7 +327,7 @@ func (api *Client) SetGroupPurposeContext(ctx context.Context, group, purpose st
 		"purpose": {purpose},
 	}
 
-	response, err := groupRequest(ctx, api.httpclient, "groups.setPurpose", values, api)
+	response, err := api.groupRequest(ctx, "groups.setPurpose", values)
 	if err != nil {
 		return "", err
 	}
@@ -347,7 +347,7 @@ func (api *Client) SetGroupTopicContext(ctx context.Context, group, topic string
 		"topic":   {topic},
 	}
 
-	response, err := groupRequest(ctx, api.httpclient, "groups.setTopic", values, api)
+	response, err := api.groupRequest(ctx, "groups.setTopic", values)
 	if err != nil {
 		return "", err
 	}
diff --git a/vendor/github.com/nlopes/slack/im.go b/vendor/github.com/nlopes/slack/im.go
index 10563d91..ee784fef 100644
--- a/vendor/github.com/nlopes/slack/im.go
+++ b/vendor/github.com/nlopes/slack/im.go
@@ -22,15 +22,13 @@ type imResponseFull struct {
 
 // IM contains information related to the Direct Message channel
 type IM struct {
-	conversation
-	IsIM          bool   `json:"is_im"`
-	User          string `json:"user"`
-	IsUserDeleted bool   `json:"is_user_deleted"`
+	Conversation
+	IsUserDeleted bool `json:"is_user_deleted"`
 }
 
-func imRequest(ctx context.Context, client httpClient, path string, values url.Values, d debug) (*imResponseFull, error) {
+func (api *Client) imRequest(ctx context.Context, path string, values url.Values) (*imResponseFull, error) {
 	response := &imResponseFull{}
-	err := postSlackMethod(ctx, client, path, values, response, d)
+	err := api.postMethod(ctx, path, values, response)
 	if err != nil {
 		return nil, err
 	}
@@ -50,7 +48,7 @@ func (api *Client) CloseIMChannelContext(ctx context.Context, channel string) (b
 		"channel": {channel},
 	}
 
-	response, err := imRequest(ctx, api.httpclient, "im.close", values, api)
+	response, err := api.imRequest(ctx, "im.close", values)
 	if err != nil {
 		return false, false, err
 	}
@@ -71,7 +69,7 @@ func (api *Client) OpenIMChannelContext(ctx context.Context, user string) (bool,
 		"user":  {user},
 	}
 
-	response, err := imRequest(ctx, api.httpclient, "im.open", values, api)
+	response, err := api.imRequest(ctx, "im.open", values)
 	if err != nil {
 		return false, false, "", err
 	}
@@ -91,7 +89,7 @@ func (api *Client) MarkIMChannelContext(ctx context.Context, channel, ts string)
 		"ts":      {ts},
 	}
 
-	_, err := imRequest(ctx, api.httpclient, "im.mark", values, api)
+	_, err := api.imRequest(ctx, "im.mark", values)
 	return err
 }
 
@@ -130,7 +128,7 @@ func (api *Client) GetIMHistoryContext(ctx context.Context, channel string, para
 		}
 	}
 
-	response, err := imRequest(ctx, api.httpclient, "im.history", values, api)
+	response, err := api.imRequest(ctx, "im.history", values)
 	if err != nil {
 		return nil, err
 	}
@@ -148,7 +146,7 @@ func (api *Client) GetIMChannelsContext(ctx context.Context) ([]IM, error) {
 		"token": {api.token},
 	}
 
-	response, err := imRequest(ctx, api.httpclient, "im.list", values, api)
+	response, err := api.imRequest(ctx, "im.list", values)
 	if err != nil {
 		return nil, err
 	}
diff --git a/vendor/github.com/nlopes/slack/info.go b/vendor/github.com/nlopes/slack/info.go
index db8534c7..31f459f1 100644
--- a/vendor/github.com/nlopes/slack/info.go
+++ b/vendor/github.com/nlopes/slack/info.go
@@ -156,17 +156,12 @@ type Icons struct {
 	Image72 string `json:"image_72,omitempty"`
 }
 
-// Info contains various details about Users, Channels, Bots and the authenticated user.
+// 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"`
-	Users    []User       `json:"users,omitempty"`
-	Channels []Channel    `json:"channels,omitempty"`
-	Groups   []Group      `json:"groups,omitempty"`
-	Bots     []Bot        `json:"bots,omitempty"`
-	IMs      []IM         `json:"ims,omitempty"`
+	URL  string       `json:"url,omitempty"`
+	User *UserDetails `json:"self,omitempty"`
+	Team *Team        `json:"team,omitempty"`
 }
 
 type infoResponseFull struct {
@@ -174,52 +169,27 @@ type infoResponseFull struct {
 	SlackResponse
 }
 
-// GetBotByID returns a bot given a bot id
+// GetBotByID is deprecated and returns nil
 func (info Info) GetBotByID(botID string) *Bot {
-	for _, bot := range info.Bots {
-		if bot.ID == botID {
-			return &bot
-		}
-	}
 	return nil
 }
 
-// GetUserByID returns a user given a user id
+// GetUserByID is deprecated and returns nil
 func (info Info) GetUserByID(userID string) *User {
-	for _, user := range info.Users {
-		if user.ID == userID {
-			return &user
-		}
-	}
 	return nil
 }
 
-// GetChannelByID returns a channel given a channel id
+// GetChannelByID is deprecated and returns nil
 func (info Info) GetChannelByID(channelID string) *Channel {
-	for _, channel := range info.Channels {
-		if channel.ID == channelID {
-			return &channel
-		}
-	}
 	return nil
 }
 
-// GetGroupByID returns a group given a group id
+// GetGroupByID is deprecated and returns nil
 func (info Info) GetGroupByID(groupID string) *Group {
-	for _, group := range info.Groups {
-		if group.ID == groupID {
-			return &group
-		}
-	}
 	return nil
 }
 
-// GetIMByID returns an IM given an IM id
+// GetIMByID is deprecated and returns nil
 func (info Info) GetIMByID(imID string) *IM {
-	for _, im := range info.IMs {
-		if im.ID == imID {
-			return &im
-		}
-	}
 	return nil
 }
diff --git a/vendor/github.com/nlopes/slack/interactions.go b/vendor/github.com/nlopes/slack/interactions.go
index addc2864..5433463d 100644
--- a/vendor/github.com/nlopes/slack/interactions.go
+++ b/vendor/github.com/nlopes/slack/interactions.go
@@ -1,8 +1,20 @@
 package slack
 
+import (
+	"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")
@@ -10,6 +22,7 @@ const (
 	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.
@@ -27,6 +40,59 @@ type InteractionCallback struct {
 	Message         Message         `json:"message"`
 	Name            string          `json:"name"`
 	Value           string          `json:"value"`
-	ActionCallback
+	MessageTs       string          `json:"message_ts"`
+	AttachmentID    string          `json:"attachment_id"`
+	ActionCallback  ActionCallbacks `json:"actions"`
 	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
+}
+
+// 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/nlopes/slack/internal/errorsx/errorsx.go b/vendor/github.com/nlopes/slack/internal/errorsx/errorsx.go
new file mode 100644
index 00000000..cb850577
--- /dev/null
+++ b/vendor/github.com/nlopes/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/nlopes/slack/internal/timex/timex.go b/vendor/github.com/nlopes/slack/internal/timex/timex.go
new file mode 100644
index 00000000..40063f73
--- /dev/null
+++ b/vendor/github.com/nlopes/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/nlopes/slack/messages.go b/vendor/github.com/nlopes/slack/messages.go
index bde9a37e..37a26335 100644
--- a/vendor/github.com/nlopes/slack/messages.go
+++ b/vendor/github.com/nlopes/slack/messages.go
@@ -16,6 +16,7 @@ type OutgoingMessage struct {
 type Message struct {
 	Msg
 	SubMessage *Msg `json:"message,omitempty"`
+	PreviousMessage *Msg `json:"previous_message,omitempty"`
 }
 
 // Msg contains information about a slack message
@@ -92,8 +93,18 @@ type Msg struct {
 	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 respone for slash commands.
+	ResponseTypeEphemeral = "ephemeral"
+)
+
 // Icon is used for bot messages
 type Icon struct {
 	IconURL   string `json:"icon_url,omitempty"`
diff --git a/vendor/github.com/nlopes/slack/misc.go b/vendor/github.com/nlopes/slack/misc.go
index 30ae4628..0dcee950 100644
--- a/vendor/github.com/nlopes/slack/misc.go
+++ b/vendor/github.com/nlopes/slack/misc.go
@@ -8,6 +8,7 @@ import (
 	"fmt"
 	"io"
 	"io/ioutil"
+	"mime"
 	"mime/multipart"
 	"net/http"
 	"net/http/httputil"
@@ -48,31 +49,95 @@ type statusCodeError struct {
 }
 
 func (t statusCodeError) Error() string {
-	// TODO: this is a bad error string, should clean it up with a breaking changes
-	// merger.
-	return fmt.Sprintf("Slack server error: %s.", t.Status)
+	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)
+	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.URL.RawQuery = (values).Encode()
+
+	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
 }
 
@@ -89,7 +154,7 @@ func parseResponseBody(body io.ReadCloser, intf interface{}, d debug) error {
 	return json.Unmarshal(response, intf)
 }
 
-func postLocalWithMultipartResponse(ctx context.Context, client httpClient, path, fpath, fieldname string, values url.Values, intf interface{}, d debug) error {
+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
@@ -99,7 +164,8 @@ func postLocalWithMultipartResponse(ctx context.Context, client httpClient, path
 		return err
 	}
 	defer file.Close()
-	return postWithMultipartResponse(ctx, client, path, filepath.Base(fpath), fieldname, values, file, intf, d)
+
+	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 {
@@ -123,7 +189,7 @@ func postWithMultipartResponse(ctx context.Context, client httpClient, path, nam
 			return
 		}
 	}()
-	req, err := fileUploadReq(ctx, APIURL+path, values, pipeReader)
+	req, err := fileUploadReq(ctx, path, values, pipeReader)
 	if err != nil {
 		return err
 	}
@@ -136,28 +202,20 @@ func postWithMultipartResponse(ctx context.Context, client httpClient, path, nam
 	}
 	defer resp.Body.Close()
 
-	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}
+	err = checkStatusCode(resp, d)
+	if err != nil {
+		return err
 	}
 
-	// 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}
-	}
 	select {
 	case err = <-errc:
 		return err
 	default:
-		return parseResponseBody(resp.Body, intf, d)
+		return newJSONParser(intf)(resp)
 	}
 }
 
-func doPost(ctx context.Context, client httpClient, req *http.Request, intf interface{}, d debug) error {
+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 {
@@ -165,21 +223,12 @@ func doPost(ctx context.Context, client httpClient, req *http.Request, intf inte
 	}
 	defer resp.Body.Close()
 
-	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}
+	err = checkStatusCode(resp, d)
+	if err != nil {
+		return err
 	}
 
-	return parseResponseBody(resp.Body, intf, d)
+	return parser(resp)
 }
 
 // post JSON.
@@ -191,7 +240,8 @@ func postJSON(ctx context.Context, client httpClient, endpoint, token string, js
 	}
 	req.Header.Set("Content-Type", "application/json")
 	req.Header.Set("Authorization", fmt.Sprintf("Bearer %s", token))
-	return doPost(ctx, client, req, intf, d)
+
+	return doPost(ctx, client, req, newJSONParser(intf), d)
 }
 
 // post a url encoded form.
@@ -202,17 +252,7 @@ func postForm(ctx context.Context, client httpClient, endpoint string, values ur
 		return err
 	}
 	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
-	return doPost(ctx, client, req, intf, d)
-}
-
-// post to a slack web method.
-func postSlackMethod(ctx context.Context, client httpClient, path string, values url.Values, intf interface{}, d debug) error {
-	return postForm(ctx, client, APIURL+path, values, intf, d)
-}
-
-// get a slack web method.
-func getSlackMethod(ctx context.Context, client httpClient, path string, values url.Values, intf interface{}, d debug) error {
-	return getResource(ctx, client, APIURL+path, values, intf, d)
+	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 {
@@ -223,7 +263,7 @@ func getResource(ctx context.Context, client httpClient, endpoint string, values
 	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
 	req.URL.RawQuery = values.Encode()
 
-	return doPost(ctx, client, req, intf, d)
+	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 {
@@ -251,12 +291,6 @@ func okJSONHandler(rw http.ResponseWriter, r *http.Request) {
 	rw.Write(response)
 }
 
-type errorString string
-
-func (t errorString) Error() string {
-	return string(t)
-}
-
 // timerReset safely reset a timer, see time.Timer.Reset for details.
 func timerReset(t *time.Timer, d time.Duration) {
 	if !t.Stop() {
@@ -264,3 +298,63 @@ func timerReset(t *time.Timer, d time.Duration) {
 	}
 	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/nlopes/slack/oauth.go b/vendor/github.com/nlopes/slack/oauth.go
index 8a8194cb..29d6dce9 100644
--- a/vendor/github.com/nlopes/slack/oauth.go
+++ b/vendor/github.com/nlopes/slack/oauth.go
@@ -57,7 +57,7 @@ func GetOAuthResponseContext(ctx context.Context, client httpClient, clientID, c
 		"redirect_uri":  {redirectURI},
 	}
 	response := &OAuthResponse{}
-	if err = postSlackMethod(ctx, client, "oauth.access", values, response, discard{}); err != nil {
+	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/nlopes/slack/pins.go b/vendor/github.com/nlopes/slack/pins.go
index c1d525df..ef97c8df 100644
--- a/vendor/github.com/nlopes/slack/pins.go
+++ b/vendor/github.com/nlopes/slack/pins.go
@@ -34,7 +34,7 @@ func (api *Client) AddPinContext(ctx context.Context, channel string, item ItemR
 	}
 
 	response := &SlackResponse{}
-	if err := postSlackMethod(ctx, api.httpclient, "pins.add", values, response, api); err != nil {
+	if err := api.postMethod(ctx, "pins.add", values, response); err != nil {
 		return err
 	}
 
@@ -63,7 +63,7 @@ func (api *Client) RemovePinContext(ctx context.Context, channel string, item It
 	}
 
 	response := &SlackResponse{}
-	if err := postSlackMethod(ctx, api.httpclient, "pins.remove", values, response, api); err != nil {
+	if err := api.postMethod(ctx, "pins.remove", values, response); err != nil {
 		return err
 	}
 
@@ -83,7 +83,7 @@ func (api *Client) ListPinsContext(ctx context.Context, channel string) ([]Item,
 	}
 
 	response := &listPinsResponseFull{}
-	err := postSlackMethod(ctx, api.httpclient, "pins.list", values, response, api)
+	err := api.postMethod(ctx, "pins.list", values, response)
 	if err != nil {
 		return nil, nil, err
 	}
diff --git a/vendor/github.com/nlopes/slack/reactions.go b/vendor/github.com/nlopes/slack/reactions.go
index abe1e72a..2a9bd42e 100644
--- a/vendor/github.com/nlopes/slack/reactions.go
+++ b/vendor/github.com/nlopes/slack/reactions.go
@@ -2,7 +2,6 @@ package slack
 
 import (
 	"context"
-	"errors"
 	"net/url"
 	"strconv"
 )
@@ -155,7 +154,7 @@ func (api *Client) AddReactionContext(ctx context.Context, name string, item Ite
 	}
 
 	response := &SlackResponse{}
-	if err := postSlackMethod(ctx, api.httpclient, "reactions.add", values, response, api); err != nil {
+	if err := api.postMethod(ctx, "reactions.add", values, response); err != nil {
 		return err
 	}
 
@@ -189,7 +188,7 @@ func (api *Client) RemoveReactionContext(ctx context.Context, name string, item
 	}
 
 	response := &SlackResponse{}
-	if err := postSlackMethod(ctx, api.httpclient, "reactions.remove", values, response, api); err != nil {
+	if err := api.postMethod(ctx, "reactions.remove", values, response); err != nil {
 		return err
 	}
 
@@ -223,12 +222,14 @@ func (api *Client) GetReactionsContext(ctx context.Context, item ItemRef, params
 	}
 
 	response := &getReactionsResponseFull{}
-	if err := postSlackMethod(ctx, api.httpclient, "reactions.get", values, response, api); err != nil {
+	if err := api.postMethod(ctx, "reactions.get", values, response); err != nil {
 		return nil, err
 	}
-	if !response.Ok {
-		return nil, errors.New(response.Error)
+
+	if err := response.Err(); err != nil {
+		return nil, err
 	}
+
 	return response.extractReactions(), nil
 }
 
@@ -256,12 +257,14 @@ func (api *Client) ListReactionsContext(ctx context.Context, params ListReaction
 	}
 
 	response := &listReactionsResponseFull{}
-	err := postSlackMethod(ctx, api.httpclient, "reactions.list", values, response, api)
+	err := api.postMethod(ctx, "reactions.list", values, response)
 	if err != nil {
 		return nil, nil, err
 	}
-	if !response.Ok {
-		return nil, nil, errors.New(response.Error)
+
+	if err := response.Err(); err != nil {
+		return nil, nil, err
 	}
+
 	return response.extractReactedItems(), &response.Paging, nil
 }
diff --git a/vendor/github.com/nlopes/slack/reminders.go b/vendor/github.com/nlopes/slack/reminders.go
index 54c91789..9b905387 100644
--- a/vendor/github.com/nlopes/slack/reminders.go
+++ b/vendor/github.com/nlopes/slack/reminders.go
@@ -23,7 +23,7 @@ type reminderResp struct {
 
 func (api *Client) doReminder(ctx context.Context, path string, values url.Values) (*Reminder, error) {
 	response := &reminderResp{}
-	if err := postSlackMethod(ctx, api.httpclient, path, values, response, api); err != nil {
+	if err := api.postMethod(ctx, path, values, response); err != nil {
 		return nil, err
 	}
 	return &response.Reminder, response.Err()
@@ -68,7 +68,7 @@ func (api *Client) DeleteReminder(id string) error {
 		"reminder": {id},
 	}
 	response := &SlackResponse{}
-	if err := postSlackMethod(context.Background(), api.httpclient, "reminders.delete", values, response, api); err != nil {
+	if err := api.postMethod(context.Background(), "reminders.delete", values, response); err != nil {
 		return err
 	}
 	return response.Err()
diff --git a/vendor/github.com/nlopes/slack/rtm.go b/vendor/github.com/nlopes/slack/rtm.go
index e7fa83f7..09cb51c3 100644
--- a/vendor/github.com/nlopes/slack/rtm.go
+++ b/vendor/github.com/nlopes/slack/rtm.go
@@ -38,7 +38,7 @@ func (api *Client) StartRTM() (info *Info, websocketURL string, err error) {
 // 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 = postSlackMethod(ctx, api.httpclient, "rtm.start", url.Values{"token": {api.token}}, response, api)
+	err = api.postMethod(ctx, "rtm.start", url.Values{"token": {api.token}}, response)
 	if err != nil {
 		return nil, "", err
 	}
@@ -63,7 +63,7 @@ func (api *Client) ConnectRTM() (info *Info, websocketURL string, err error) {
 // 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 = postSlackMethod(ctx, api.httpclient, "rtm.connect", url.Values{"token": {api.token}}, response, api)
+	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
@@ -112,14 +112,13 @@ func RTMOptionConnParams(connParams url.Values) RTMOption {
 func (api *Client) NewRTM(options ...RTMOption) *RTM {
 	result := &RTM{
 		Client:           *api,
-		wasIntentional:   true,
-		isConnected:      false,
 		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{}, 1),
+		disconnected:     make(chan struct{}),
+		disconnectedm:    &sync.Once{},
 		forcePing:        make(chan bool),
 		rawEvents:        make(chan json.RawMessage),
 		idGen:            NewSafeID(1),
diff --git a/vendor/github.com/nlopes/slack/search.go b/vendor/github.com/nlopes/slack/search.go
index 2d018fcc..67e3b1d1 100644
--- a/vendor/github.com/nlopes/slack/search.go
+++ b/vendor/github.com/nlopes/slack/search.go
@@ -41,6 +41,7 @@ type SearchMessage struct {
 	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"`
@@ -103,7 +104,7 @@ func (api *Client) _search(ctx context.Context, path, query string, params Searc
 	}
 
 	response = &searchResponseFull{}
-	err := postSlackMethod(ctx, api.httpclient, path, values, response, api)
+	err := api.postMethod(ctx, path, values, response)
 	if err != nil {
 		return nil, err
 	}
diff --git a/vendor/github.com/nlopes/slack/security.go b/vendor/github.com/nlopes/slack/security.go
index 35727027..dbe8fb2d 100644
--- a/vendor/github.com/nlopes/slack/security.go
+++ b/vendor/github.com/nlopes/slack/security.go
@@ -4,7 +4,6 @@ import (
 	"crypto/hmac"
 	"crypto/sha256"
 	"encoding/hex"
-	"errors"
 	"fmt"
 	"hash"
 	"net/http"
@@ -34,7 +33,7 @@ func unsafeSignatureVerifier(header http.Header, secret string) (_ SecretsVerifi
 	stimestamp := header.Get(hTimestamp)
 
 	if signature == "" || stimestamp == "" {
-		return SecretsVerifier{}, errors.New("missing headers")
+		return SecretsVerifier{}, ErrMissingHeaders
 	}
 
 	if bsignature, err = hex.DecodeString(strings.TrimPrefix(signature, "v0=")); err != nil {
@@ -70,7 +69,7 @@ func NewSecretsVerifier(header http.Header, secret string) (sv SecretsVerifier,
 
 	diff := absDuration(time.Since(time.Unix(timestamp, 0)))
 	if diff > 5*time.Minute {
-		return SecretsVerifier{}, fmt.Errorf("timestamp is too old")
+		return SecretsVerifier{}, ErrExpiredTimestamp
 	}
 
 	return sv, err
@@ -88,7 +87,7 @@ func (v SecretsVerifier) Ensure() error {
 		return nil
 	}
 
-	return fmt.Errorf("Expected signing signature: %s, but computed: %s", v.signature, computed)
+	return fmt.Errorf("Expected signing signature: %s, but computed: %s", hex.EncodeToString(v.signature), hex.EncodeToString(computed))
 }
 
 func abs64(n int64) int64 {
diff --git a/vendor/github.com/nlopes/slack/slack.go b/vendor/github.com/nlopes/slack/slack.go
index c1ba0fc3..94230526 100644
--- a/vendor/github.com/nlopes/slack/slack.go
+++ b/vendor/github.com/nlopes/slack/slack.go
@@ -9,11 +9,12 @@ import (
 	"os"
 )
 
-// APIURL added as a var so that we can change this for testing purposes
-var APIURL = "https://slack.com/api/"
-
-// WEBAPIURLFormat ...
-const WEBAPIURLFormat = "https://%s.slack.com/api/users.admin.%s?t=%d"
+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 {
@@ -40,6 +41,8 @@ type AuthTestResponse struct {
 	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 {
@@ -48,8 +51,11 @@ type authTestResponseFull struct {
 }
 
 // Client for the slack api.
+type ParamOption func(*url.Values)
+
 type Client struct {
 	token      string
+	endpoint   string
 	debug      bool
 	log        ilogger
 	httpclient httpClient
@@ -79,10 +85,16 @@ func OptionLog(l logger) func(*Client) {
 	}
 }
 
+// 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, "nlopes/slack", log.LstdFlags|log.Lshortfile),
 	}
@@ -103,7 +115,7 @@ func (api *Client) AuthTest() (response *AuthTestResponse, error error) {
 func (api *Client) AuthTestContext(ctx context.Context) (response *AuthTestResponse, err error) {
 	api.Debugf("Challenging auth...")
 	responseFull := &authTestResponseFull{}
-	err = postSlackMethod(ctx, api.httpclient, "auth.test", url.Values{"token": {api.token}}, responseFull, api)
+	err = api.postMethod(ctx, "auth.test", url.Values{"token": {api.token}}, responseFull)
 	if err != nil {
 		return nil, err
 	}
@@ -129,3 +141,13 @@ func (api *Client) Debugln(v ...interface{}) {
 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/nlopes/slack/slackutilsx/slackutilsx.go b/vendor/github.com/nlopes/slack/slackutilsx/slackutilsx.go
index ccf5372b..1f7b2b8c 100644
--- a/vendor/github.com/nlopes/slack/slackutilsx/slackutilsx.go
+++ b/vendor/github.com/nlopes/slack/slackutilsx/slackutilsx.go
@@ -55,3 +55,8 @@ 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/nlopes/slack/stars.go b/vendor/github.com/nlopes/slack/stars.go
index 7e1e621d..e84d0447 100644
--- a/vendor/github.com/nlopes/slack/stars.go
+++ b/vendor/github.com/nlopes/slack/stars.go
@@ -2,7 +2,6 @@ package slack
 
 import (
 	"context"
-	"errors"
 	"net/url"
 	"strconv"
 )
@@ -58,7 +57,7 @@ func (api *Client) AddStarContext(ctx context.Context, channel string, item Item
 	}
 
 	response := &SlackResponse{}
-	if err := postSlackMethod(ctx, api.httpclient, "stars.add", values, response, api); err != nil {
+	if err := api.postMethod(ctx, "stars.add", values, response); err != nil {
 		return err
 	}
 
@@ -87,7 +86,7 @@ func (api *Client) RemoveStarContext(ctx context.Context, channel string, item I
 	}
 
 	response := &SlackResponse{}
-	if err := postSlackMethod(ctx, api.httpclient, "stars.remove", values, response, api); err != nil {
+	if err := api.postMethod(ctx, "stars.remove", values, response); err != nil {
 		return err
 	}
 
@@ -115,13 +114,15 @@ func (api *Client) ListStarsContext(ctx context.Context, params StarsParameters)
 	}
 
 	response := &listResponseFull{}
-	err := postSlackMethod(ctx, api.httpclient, "stars.list", values, response, api)
+	err := api.postMethod(ctx, "stars.list", values, response)
 	if err != nil {
 		return nil, nil, err
 	}
-	if !response.Ok {
-		return nil, nil, errors.New(response.Error)
+
+	if err := response.Err(); err != nil {
+		return nil, nil, err
 	}
+
 	return response.Items, &response.Paging, nil
 }
 
diff --git a/vendor/github.com/nlopes/slack/team.go b/vendor/github.com/nlopes/slack/team.go
index 1892cf5f..029e2b5b 100644
--- a/vendor/github.com/nlopes/slack/team.go
+++ b/vendor/github.com/nlopes/slack/team.go
@@ -66,9 +66,9 @@ func NewAccessLogParameters() AccessLogParameters {
 	}
 }
 
-func teamRequest(ctx context.Context, client httpClient, path string, values url.Values, d debug) (*TeamResponse, error) {
+func (api *Client) teamRequest(ctx context.Context, path string, values url.Values) (*TeamResponse, error) {
 	response := &TeamResponse{}
-	err := postSlackMethod(ctx, client, path, values, response, d)
+	err := api.postMethod(ctx, path, values, response)
 	if err != nil {
 		return nil, err
 	}
@@ -76,9 +76,9 @@ func teamRequest(ctx context.Context, client httpClient, path string, values url
 	return response, response.Err()
 }
 
-func billableInfoRequest(ctx context.Context, client httpClient, path string, values url.Values, d debug) (map[string]BillingActive, error) {
+func (api *Client) billableInfoRequest(ctx context.Context, path string, values url.Values) (map[string]BillingActive, error) {
 	response := &BillableInfoResponse{}
-	err := postSlackMethod(ctx, client, path, values, response, d)
+	err := api.postMethod(ctx, path, values, response)
 	if err != nil {
 		return nil, err
 	}
@@ -86,9 +86,9 @@ func billableInfoRequest(ctx context.Context, client httpClient, path string, va
 	return response.BillableInfo, response.Err()
 }
 
-func accessLogsRequest(ctx context.Context, client httpClient, path string, values url.Values, d debug) (*LoginResponse, error) {
+func (api *Client) accessLogsRequest(ctx context.Context, path string, values url.Values) (*LoginResponse, error) {
 	response := &LoginResponse{}
-	err := postSlackMethod(ctx, client, path, values, response, d)
+	err := api.postMethod(ctx, path, values, response)
 	if err != nil {
 		return nil, err
 	}
@@ -106,7 +106,7 @@ func (api *Client) GetTeamInfoContext(ctx context.Context) (*TeamInfo, error) {
 		"token": {api.token},
 	}
 
-	response, err := teamRequest(ctx, api.httpclient, "team.info", values, api)
+	response, err := api.teamRequest(ctx, "team.info", values)
 	if err != nil {
 		return nil, err
 	}
@@ -130,24 +130,26 @@ func (api *Client) GetAccessLogsContext(ctx context.Context, params AccessLogPar
 		values.Add("page", strconv.Itoa(params.Page))
 	}
 
-	response, err := accessLogsRequest(ctx, api.httpclient, "team.accessLogs", values, api)
+	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 billableInfoRequest(ctx, api.httpclient, "team.billableInfo", values, api)
+	return api.billableInfoRequest(ctx, "team.billableInfo", values)
 }
 
 // GetBillableInfoForTeam returns the billing_active status of all users on the team.
@@ -161,5 +163,5 @@ func (api *Client) GetBillableInfoForTeamContext(ctx context.Context) (map[strin
 		"token": {api.token},
 	}
 
-	return billableInfoRequest(ctx, api.httpclient, "team.billableInfo", values, api)
+	return api.billableInfoRequest(ctx, "team.billableInfo", values)
 }
diff --git a/vendor/github.com/nlopes/slack/usergroups.go b/vendor/github.com/nlopes/slack/usergroups.go
index 9e145272..f3206591 100644
--- a/vendor/github.com/nlopes/slack/usergroups.go
+++ b/vendor/github.com/nlopes/slack/usergroups.go
@@ -40,9 +40,9 @@ type userGroupResponseFull struct {
 	SlackResponse
 }
 
-func userGroupRequest(ctx context.Context, client httpClient, path string, values url.Values, d debug) (*userGroupResponseFull, error) {
+func (api *Client) userGroupRequest(ctx context.Context, path string, values url.Values) (*userGroupResponseFull, error) {
 	response := &userGroupResponseFull{}
-	err := postSlackMethod(ctx, client, path, values, response, d)
+	err := api.postMethod(ctx, path, values, response)
 	if err != nil {
 		return nil, err
 	}
@@ -74,7 +74,7 @@ func (api *Client) CreateUserGroupContext(ctx context.Context, userGroup UserGro
 		values["channels"] = []string{strings.Join(userGroup.Prefs.Channels, ",")}
 	}
 
-	response, err := userGroupRequest(ctx, api.httpclient, "usergroups.create", values, api)
+	response, err := api.userGroupRequest(ctx, "usergroups.create", values)
 	if err != nil {
 		return UserGroup{}, err
 	}
@@ -93,7 +93,7 @@ func (api *Client) DisableUserGroupContext(ctx context.Context, userGroup string
 		"usergroup": {userGroup},
 	}
 
-	response, err := userGroupRequest(ctx, api.httpclient, "usergroups.disable", values, api)
+	response, err := api.userGroupRequest(ctx, "usergroups.disable", values)
 	if err != nil {
 		return UserGroup{}, err
 	}
@@ -112,7 +112,7 @@ func (api *Client) EnableUserGroupContext(ctx context.Context, userGroup string)
 		"usergroup": {userGroup},
 	}
 
-	response, err := userGroupRequest(ctx, api.httpclient, "usergroups.enable", values, api)
+	response, err := api.userGroupRequest(ctx, "usergroups.enable", values)
 	if err != nil {
 		return UserGroup{}, err
 	}
@@ -176,7 +176,7 @@ func (api *Client) GetUserGroupsContext(ctx context.Context, options ...GetUserG
 		values.Add("include_users", "true")
 	}
 
-	response, err := userGroupRequest(ctx, api.httpclient, "usergroups.list", values, api)
+	response, err := api.userGroupRequest(ctx, "usergroups.list", values)
 	if err != nil {
 		return nil, err
 	}
@@ -206,8 +206,12 @@ func (api *Client) UpdateUserGroupContext(ctx context.Context, userGroup UserGro
 	if userGroup.Description != "" {
 		values["description"] = []string{userGroup.Description}
 	}
+	
+	if len(userGroup.Prefs.Channels) > 0 {
+		values["channels"] = []string{strings.Join(userGroup.Prefs.Channels, ",")}
+	}
 
-	response, err := userGroupRequest(ctx, api.httpclient, "usergroups.update", values, api)
+	response, err := api.userGroupRequest(ctx, "usergroups.update", values)
 	if err != nil {
 		return UserGroup{}, err
 	}
@@ -226,7 +230,7 @@ func (api *Client) GetUserGroupMembersContext(ctx context.Context, userGroup str
 		"usergroup": {userGroup},
 	}
 
-	response, err := userGroupRequest(ctx, api.httpclient, "usergroups.users.list", values, api)
+	response, err := api.userGroupRequest(ctx, "usergroups.users.list", values)
 	if err != nil {
 		return []string{}, err
 	}
@@ -246,7 +250,7 @@ func (api *Client) UpdateUserGroupMembersContext(ctx context.Context, userGroup
 		"users":     {members},
 	}
 
-	response, err := userGroupRequest(ctx, api.httpclient, "usergroups.users.update", values, api)
+	response, err := api.userGroupRequest(ctx, "usergroups.users.update", values)
 	if err != nil {
 		return UserGroup{}, err
 	}
diff --git a/vendor/github.com/nlopes/slack/users.go b/vendor/github.com/nlopes/slack/users.go
index 74b79372..4da8e4ce 100644
--- a/vendor/github.com/nlopes/slack/users.go
+++ b/vendor/github.com/nlopes/slack/users.go
@@ -3,16 +3,15 @@ package slack
 import (
 	"context"
 	"encoding/json"
-	"errors"
 	"net/url"
 	"strconv"
+	"time"
 )
 
 const (
 	DEFAULT_USER_PHOTO_CROP_X = -1
 	DEFAULT_USER_PHOTO_CROP_Y = -1
 	DEFAULT_USER_PHOTO_CROP_W = -1
-	errPaginationComplete     = errorString("pagination complete")
 )
 
 // UserProfile contains all the information details of a given user
@@ -37,6 +36,7 @@ type UserProfile struct {
 	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"`
 }
@@ -100,28 +100,31 @@ type UserProfileCustomField struct {
 
 // 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"`
-	Has2FA            bool        `json:"has_2fa"`
-	HasFiles          bool        `json:"has_files"`
-	Presence          string      `json:"presence"`
-	Locale            string      `json:"locale"`
+	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
@@ -152,6 +155,17 @@ type UserIdentity struct {
 	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"`
@@ -189,9 +203,9 @@ func NewUserSetPhotoParams() UserSetPhotoParams {
 	}
 }
 
-func userRequest(ctx context.Context, client httpClient, path string, values url.Values, d debug) (*userResponseFull, error) {
+func (api *Client) userRequest(ctx context.Context, path string, values url.Values) (*userResponseFull, error) {
 	response := &userResponseFull{}
-	err := postForm(ctx, client, APIURL+path, values, response, d)
+	err := api.postMethod(ctx, path, values, response)
 	if err != nil {
 		return nil, err
 	}
@@ -211,7 +225,7 @@ func (api *Client) GetUserPresenceContext(ctx context.Context, user string) (*Us
 		"user":  {user},
 	}
 
-	response, err := userRequest(ctx, api.httpclient, "users.getPresence", values, api)
+	response, err := api.userRequest(ctx, "users.getPresence", values)
 	if err != nil {
 		return nil, err
 	}
@@ -231,7 +245,7 @@ func (api *Client) GetUserInfoContext(ctx context.Context, user string) (*User,
 		"include_locale": {strconv.FormatBool(true)},
 	}
 
-	response, err := userRequest(ctx, api.httpclient, "users.info", values, api)
+	response, err := api.userRequest(ctx, "users.info", values)
 	if err != nil {
 		return nil, err
 	}
@@ -310,7 +324,7 @@ func (t UserPagination) Next(ctx context.Context) (_ UserPagination, err error)
 		"include_locale": {strconv.FormatBool(true)},
 	}
 
-	if resp, err = userRequest(ctx, t.c.httpclient, "users.list", values, t.c); err != nil {
+	if resp, err = t.c.userRequest(ctx, "users.list", values); err != nil {
 		return t, err
 	}
 
@@ -333,12 +347,19 @@ func (api *Client) GetUsers() ([]User, error) {
 
 // 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) {
-	var (
-		p UserPagination
-	)
-
-	for p = api.GetUsersPaginated(); !p.Done(err); p, err = p.Next(ctx) {
-		results = append(results, p.Users...)
+	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)
@@ -355,7 +376,7 @@ func (api *Client) GetUserByEmailContext(ctx context.Context, email string) (*Us
 		"token": {api.token},
 		"email": {email},
 	}
-	response, err := userRequest(ctx, api.httpclient, "users.lookupByEmail", values, api)
+	response, err := api.userRequest(ctx, "users.lookupByEmail", values)
 	if err != nil {
 		return nil, err
 	}
@@ -373,7 +394,7 @@ func (api *Client) SetUserAsActiveContext(ctx context.Context) (err error) {
 		"token": {api.token},
 	}
 
-	_, err = userRequest(ctx, api.httpclient, "users.setActive", values, api)
+	_, err = api.userRequest(ctx, "users.setActive", values)
 	return err
 }
 
@@ -389,7 +410,7 @@ func (api *Client) SetUserPresenceContext(ctx context.Context, presence string)
 		"presence": {presence},
 	}
 
-	_, err := userRequest(ctx, api.httpclient, "users.setPresence", values, api)
+	_, err := api.userRequest(ctx, "users.setPresence", values)
 	return err
 }
 
@@ -399,19 +420,21 @@ func (api *Client) GetUserIdentity() (*UserIdentityResponse, error) {
 }
 
 // GetUserIdentityContext will retrieve user info available per identity scopes with a custom context
-func (api *Client) GetUserIdentityContext(ctx context.Context) (*UserIdentityResponse, error) {
+func (api *Client) GetUserIdentityContext(ctx context.Context) (response *UserIdentityResponse, err error) {
 	values := url.Values{
 		"token": {api.token},
 	}
-	response := &UserIdentityResponse{}
+	response = &UserIdentityResponse{}
 
-	err := postForm(ctx, api.httpclient, APIURL+"users.identity", values, response, api)
+	err = api.postMethod(ctx, "users.identity", values, response)
 	if err != nil {
 		return nil, err
 	}
-	if !response.Ok {
-		return nil, errors.New(response.Error)
+
+	if err := response.Err(); err != nil {
+		return nil, err
 	}
+
 	return response, nil
 }
 
@@ -421,7 +444,7 @@ func (api *Client) SetUserPhoto(image string, params UserSetPhotoParams) error {
 }
 
 // SetUserPhotoContext changes the currently authenticated user's profile image using a custom context
-func (api *Client) SetUserPhotoContext(ctx context.Context, image string, params UserSetPhotoParams) error {
+func (api *Client) SetUserPhotoContext(ctx context.Context, image string, params UserSetPhotoParams) (err error) {
 	response := &SlackResponse{}
 	values := url.Values{
 		"token": {api.token},
@@ -436,7 +459,7 @@ func (api *Client) SetUserPhotoContext(ctx context.Context, image string, params
 		values.Add("crop_w", strconv.Itoa(params.CropW))
 	}
 
-	err := postLocalWithMultipartResponse(ctx, api.httpclient, "users.setPhoto", image, "image", values, response, api)
+	err = postLocalWithMultipartResponse(ctx, api.httpclient, api.endpoint+"users.setPhoto", image, "image", values, response, api)
 	if err != nil {
 		return err
 	}
@@ -450,13 +473,13 @@ func (api *Client) DeleteUserPhoto() error {
 }
 
 // DeleteUserPhotoContext deletes the current authenticated user's profile image with a custom context
-func (api *Client) DeleteUserPhotoContext(ctx context.Context) error {
+func (api *Client) DeleteUserPhotoContext(ctx context.Context) (err error) {
 	response := &SlackResponse{}
 	values := url.Values{
 		"token": {api.token},
 	}
 
-	err := postForm(ctx, api.httpclient, APIURL+"users.deletePhoto", values, response, api)
+	err = api.postMethod(ctx, "users.deletePhoto", values, response)
 	if err != nil {
 		return err
 	}
@@ -467,15 +490,30 @@ func (api *Client) DeleteUserPhotoContext(ctx context.Context) error {
 // 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.
-func (api *Client) SetUserCustomStatus(statusText, statusEmoji string) error {
-	return api.SetUserCustomStatusContext(context.Background(), statusText, statusEmoji)
+// 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) error {
+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.
@@ -488,11 +526,13 @@ func (api *Client) SetUserCustomStatusContext(ctx context.Context, statusText, s
 	// - 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"`
+			StatusText       string `json:"status_text"`
+			StatusEmoji      string `json:"status_emoji"`
+			StatusExpiration int64  `json:"status_expiration"`
 		}{
-			StatusText:  statusText,
-			StatusEmoji: statusEmoji,
+			StatusText:       statusText,
+			StatusEmoji:      statusEmoji,
+			StatusExpiration: statusExpiration,
 		},
 	)
 
@@ -501,20 +541,17 @@ func (api *Client) SetUserCustomStatusContext(ctx context.Context, statusText, s
 	}
 
 	values := url.Values{
+		"user":    {user},
 		"token":   {api.token},
 		"profile": {string(profile)},
 	}
 
 	response := &userResponseFull{}
-	if err = postForm(ctx, api.httpclient, APIURL+"users.profile.set", values, response, api); err != nil {
+	if err = api.postMethod(ctx, "users.profile.set", values, response); err != nil {
 		return err
 	}
 
-	if !response.Ok {
-		return errors.New(response.Error)
-	}
-
-	return nil
+	return response.Err()
 }
 
 // UnsetUserCustomStatus removes the custom status message for the currently
@@ -526,7 +563,7 @@ func (api *Client) UnsetUserCustomStatus() error {
 // 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, "", "")
+	return api.SetUserCustomStatusContext(ctx, "", "", 0)
 }
 
 // GetUserProfile retrieves a user's profile information.
@@ -547,12 +584,14 @@ func (api *Client) GetUserProfileContext(ctx context.Context, userID string, inc
 	}
 	resp := &getUserProfileResponse{}
 
-	err := postSlackMethod(ctx, api.httpclient, "users.profile.get", values, &resp, api)
+	err := api.postMethod(ctx, "users.profile.get", values, &resp)
 	if err != nil {
 		return nil, err
 	}
-	if !resp.Ok {
-		return nil, errors.New(resp.Error)
+
+	if err := resp.Err(); err != nil {
+		return nil, err
 	}
+
 	return resp.Profile, nil
 }
diff --git a/vendor/github.com/nlopes/slack/webhooks.go b/vendor/github.com/nlopes/slack/webhooks.go
index 3ea69ffe..14e1b8dd 100644
--- a/vendor/github.com/nlopes/slack/webhooks.go
+++ b/vendor/github.com/nlopes/slack/webhooks.go
@@ -9,26 +9,32 @@ import (
 )
 
 type WebhookMessage struct {
-	Text        string       `json:"text,omitempty"`
-	Attachments []Attachment `json:"attachments,omitempty"`
+	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 PostWebhookCustomHTTP(url, http.DefaultClient, msg)
+}
+
+func PostWebhookCustomHTTP(url string, httpClient *http.Client, msg *WebhookMessage) error {
 	raw, err := json.Marshal(msg)
 
 	if err != nil {
 		return errors.Wrap(err, "marshal failed")
 	}
 
-	response, err := http.Post(url, "application/json", bytes.NewReader(raw))
+	response, err := httpClient.Post(url, "application/json", bytes.NewReader(raw))
 
 	if err != nil {
 		return errors.Wrap(err, "failed to post webhook")
 	}
 
-	if response.StatusCode != http.StatusOK {
-		return statusCodeError{Code: response.StatusCode, Status: response.Status}
-	}
-
-	return nil
+	return checkStatusCode(response, discard{})
 }
diff --git a/vendor/github.com/nlopes/slack/websocket.go b/vendor/github.com/nlopes/slack/websocket.go
index e5dee68a..122807b9 100644
--- a/vendor/github.com/nlopes/slack/websocket.go
+++ b/vendor/github.com/nlopes/slack/websocket.go
@@ -2,7 +2,6 @@ package slack
 
 import (
 	"encoding/json"
-	"errors"
 	"net/url"
 	"sync"
 	"time"
@@ -33,11 +32,10 @@ type RTM struct {
 	IncomingEvents   chan RTMEvent
 	outgoingMessages chan OutgoingMessage
 	killChannel      chan bool
-	disconnected     chan struct{} // disconnected is closed when Disconnect is invoked, regardless of connection state. Allows for ManagedConnection to not leak.
+	disconnected     chan struct{}
+	disconnectedm    *sync.Once
 	forcePing        chan bool
 	rawEvents        chan json.RawMessage
-	wasIntentional   bool
-	isConnected      bool
 
 	// UserDetails upon connection
 	info *Info
@@ -58,32 +56,30 @@ type RTM struct {
 	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 {
-	// avoid RTM disconnect race conditions
-	rtm.mu.Lock()
-	defer rtm.mu.Unlock()
-
-	// always push into the disconnected channel when invoked,
+	// 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.disconnected <- struct{}{}:
-	default:
+	case rtm.killChannel <- true:
+		return nil
+	case <-rtm.disconnected:
+		return ErrAlreadyDisconnected
 	}
-
-	if !rtm.isConnected {
-		return errors.New("Invalid call to Disconnect - Slack API is already disconnected")
-	}
-
-	rtm.killChannel <- true
-	return nil
 }
 
 // GetInfo returns the info structure received when calling
-// "startrtm", holding all channels, groups and other metadata needed
-// to implement a full chat client. It will be non-nil after a call to
-// StartRTM().
+// "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
 }
diff --git a/vendor/github.com/nlopes/slack/websocket_internals.go b/vendor/github.com/nlopes/slack/websocket_internals.go
index e8374b0d..3e1906ee 100644
--- a/vendor/github.com/nlopes/slack/websocket_internals.go
+++ b/vendor/github.com/nlopes/slack/websocket_internals.go
@@ -18,6 +18,7 @@ type ConnectedEvent struct {
 // 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
 }
 
@@ -34,6 +35,7 @@ type ConnectingEvent struct {
 // DisconnectedEvent contains information about how we disconnected
 type DisconnectedEvent struct {
 	Intentional bool
+	Cause       error
 }
 
 // LatencyReport contains information about connection latency
diff --git a/vendor/github.com/nlopes/slack/websocket_managed_conn.go b/vendor/github.com/nlopes/slack/websocket_managed_conn.go
index 62157910..8b3b3833 100644
--- a/vendor/github.com/nlopes/slack/websocket_managed_conn.go
+++ b/vendor/github.com/nlopes/slack/websocket_managed_conn.go
@@ -10,6 +10,8 @@ import (
 	"time"
 
 	"github.com/gorilla/websocket"
+	"github.com/nlopes/slack/internal/errorsx"
+	"github.com/nlopes/slack/internal/timex"
 )
 
 // ManageConnection can be called on a Slack RTM instance returned by the
@@ -38,6 +40,7 @@ func (rtm *RTM) ManageConnection() {
 		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
 		}
 
@@ -45,7 +48,6 @@ func (rtm *RTM) ManageConnection() {
 		// and conn.
 		rtm.mu.Lock()
 		rtm.conn = conn
-		rtm.isConnected = true
 		rtm.info = info
 		rtm.mu.Unlock()
 
@@ -56,20 +58,19 @@ func (rtm *RTM) ManageConnection() {
 
 		rtm.Debugf("RTM connection succeeded on try %d", connectionCount)
 
-		keepRunning := make(chan bool)
-		// we're now connected (or have failed fatally) so we can set up
-		// listeners
-		go rtm.handleIncomingEvents(keepRunning)
+		// we're now connected so we can set up listeners
+		go rtm.handleIncomingEvents()
 
 		// this should be a blocking call until the connection has ended
-		rtm.handleEvents(keepRunning)
+		rtm.handleEvents()
 
-		// after being disconnected we need to check if it was intentional
-		// if not then we should try to reconnect
-		if rtm.wasIntentional {
+		select {
+		case <-rtm.disconnected:
+			// after handle events returns we need to check if we're disconnected
 			return
+		default:
+			// otherwise continue and run the loop again to reconnect
 		}
-		// else continue and run the loop again to connect
 	}
 }
 
@@ -88,18 +89,20 @@ func (rtm *RTM) connect(connectionCount int, useRTMStart bool) (*Info, *websocke
 	// used to provide exponential backoff wait time with jitter before trying
 	// to connect to slack again
 	boff := &backoff{
-		Min:    100 * time.Millisecond,
-		Max:    5 * time.Minute,
-		Factor: 2,
-		Jitter: true,
+		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 {
@@ -109,32 +112,49 @@ func (rtm *RTM) connect(connectionCount int, useRTMStart bool) (*Info, *websocke
 		// check for fatal errors
 		switch err.Error() {
 		case errInvalidAuth, errInactiveAccount, errMissingAuthToken:
-			rtm.Debugf("Invalid auth when connecting with RTM: %s", err)
+			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,
 		}}
 
-		// check if Disconnect() has been invoked.
+		// 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:
-			rtm.IncomingEvents <- RTMEvent{"disconnected", &DisconnectedEvent{Intentional: true}}
-			return nil, nil, fmt.Errorf("disconnect received while trying to connect")
-		default:
+			return nil, nil, ErrRTMDisconnected
 		}
-
-		// get time we should wait before attempting to connect again
-		dur := boff.Duration()
-		rtm.Debugf("reconnection %d failed: %s", boff.attempts+1, err)
-		rtm.Debugln(" -> reconnecting in", dur)
-		time.Sleep(dur)
 	}
 }
 
@@ -187,15 +207,19 @@ func (rtm *RTM) startRTMAndDial(useRTMStart bool) (info *Info, _ *websocket.Conn
 //
 // 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(keepRunning chan bool, intentional bool) error {
+func (rtm *RTM) killConnection(intentional bool, cause error) (err error) {
 	rtm.Debugln("killing connection")
-	if rtm.isConnected {
-		close(keepRunning)
+
+	if rtm.conn != nil {
+		err = rtm.conn.Close()
+	}
+
+	rtm.IncomingEvents <- RTMEvent{"disconnected", &DisconnectedEvent{Intentional: intentional, Cause: cause}}
+
+	if intentional {
+		rtm.disconnect()
 	}
-	rtm.isConnected = false
-	rtm.wasIntentional = intentional
-	err := rtm.conn.Close()
-	rtm.IncomingEvents <- RTMEvent{"disconnected", &DisconnectedEvent{intentional}}
+
 	return err
 }
 
@@ -204,31 +228,28 @@ func (rtm *RTM) killConnection(keepRunning chan bool, intentional bool) error {
 // 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(keepRunning chan bool) {
+func (rtm *RTM) handleEvents() {
 	ticker := time.NewTicker(rtm.pingInterval)
 	defer ticker.Stop()
 	for {
 		select {
 		// catch "stop" signal on channel close
 		case intentional := <-rtm.killChannel:
-			_ = rtm.killConnection(keepRunning, intentional)
+			_ = rtm.killConnection(intentional, errorsx.String("signaled"))
 			return
-
 		// detect when the connection is dead.
 		case <-rtm.pingDeadman.C:
-			rtm.Debugln("deadman switch trigger disconnecting")
-			_ = rtm.killConnection(keepRunning, false)
+			_ = rtm.killConnection(false, errorsx.String("deadman switch triggered"))
+			return
 		// send pings on ticker interval
 		case <-ticker.C:
-			err := rtm.ping()
-			if err != nil {
-				_ = rtm.killConnection(keepRunning, false)
+			if err := rtm.ping(); err != nil {
+				_ = rtm.killConnection(false, err)
 				return
 			}
 		case <-rtm.forcePing:
-			err := rtm.ping()
-			if err != nil {
-				_ = rtm.killConnection(keepRunning, false)
+			if err := rtm.ping(); err != nil {
+				_ = rtm.killConnection(false, err)
 				return
 			}
 		// listen for messages that need to be sent
@@ -238,7 +259,8 @@ func (rtm *RTM) handleEvents(keepRunning chan bool) {
 		case rawEvent := <-rtm.rawEvents:
 			switch rtm.handleRawEvent(rawEvent) {
 			case rtmEventTypeGoodbye:
-				_ = rtm.killConnection(keepRunning, false)
+				_ = rtm.killConnection(false, errorsx.String("goodbye detected"))
+				return
 			default:
 			}
 		}
@@ -250,17 +272,10 @@ func (rtm *RTM) handleEvents(keepRunning chan bool) {
 //
 // This will stop executing once the RTM's keepRunning channel has been closed
 // or has anything sent to it.
-func (rtm *RTM) handleIncomingEvents(keepRunning <-chan bool) {
+func (rtm *RTM) handleIncomingEvents() {
 	for {
-		// non-blocking listen to see if channel is closed
-		select {
-		// catch "stop" signal on channel close
-		case <-keepRunning:
+		if err := rtm.receiveIncomingEvent(); err != nil {
 			return
-		default:
-			if err := rtm.receiveIncomingEvent(); err != nil {
-				return
-			}
 		}
 	}
 }
@@ -296,7 +311,6 @@ func (rtm *RTM) sendOutgoingMessage(msg OutgoingMessage) {
 			Message:  msg,
 			ErrorObj: err,
 		}}
-		// TODO force ping?
 	}
 }
 
@@ -332,20 +346,32 @@ func (rtm *RTM) receiveIncomingEvent() error {
 		// 'PING' message
 
 		// trigger a 'PING' to detect potential websocket disconnect
-		rtm.forcePing <- true
+		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,
 		}}
-		rtm.killChannel <- false
+
+		select {
+		case rtm.killChannel <- false:
+		case <-rtm.disconnected:
+		}
+
 		return err
 	case len(event) == 0:
 		rtm.Debugln("Received empty event")
 	default:
-		rtm.Debugln("Incoming Event:", string(event[:]))
-		rtm.rawEvents <- event
+		rtm.Debugln("Incoming Event:", string(event))
+		select {
+		case rtm.rawEvents <- event:
+		case <-rtm.disconnected:
+			rtm.Debugln("disonnected while attempting to send raw event")
+		}
 	}
 	return nil
 }