Add new webhooks for Labels and Milestones

Fixes #460.
Closes #463.

Change-Id: I34688c42a9328af10b4b61546e8bfd2c95c893aa

github/activity_events.go

@@ -55,10 +55,14 @@ func (e *Event) Payload() (payload interface{}) {
 		payload = &IssueCommentEvent{}
 	case "IssuesEvent":
 		payload = &IssuesEvent{}
+	case "LabelEvent":
+		payload = &LabelEvent{}
 	case "MemberEvent":
 		payload = &MemberEvent{}
 	case "MembershipEvent":
 		payload = &MembershipEvent{}
+	case "MilestoneEvent":
+		payload = &MilestoneEvent{}
 	case "PageBuildEvent":
 		payload = &PageBuildEvent{}
 	case "PublicEvent":

github/event_types.go

@@ -209,6 +209,22 @@ type IssuesEvent struct {
 	Sender  *User       `json:"sender,omitempty"`
 }
 
+// LabelEvent is triggered when a repository's label is created, edited, or deleted.
+// The Webhook event name is "label"
+//
+// GitHub docs: https://developer.github.com/v3/activity/events/types/#labelevent
+type LabelEvent struct {
+	// Action is the action that was performed. Possible values are:
+	// "created", "edited", "deleted"
+	Action *string `json:"action,omitempty"`
+	Label  *Label  `json:"label,omitempty"`
+
+	// The following fields are only populated by Webhook events.
+	Changes *EditChange   `json:"changes,omitempty"`
+	Repo    *Repository   `json:"repository,omitempty"`
+	Org     *Organization `json:"organization,omitempty"`
+}
+
 // MemberEvent is triggered when a user is added as a collaborator to a repository.
 // The Webhook event name is "member".
 //
@@ -243,6 +259,23 @@ type MembershipEvent struct {
 	Sender *User         `json:"sender,omitempty"`
 }
 
+// MilestoneEvent is triggered when a milestone is created, closed, opened, edited, or deleted.
+// The Webhook event name is "milestone".
+//
+// Github docs: https://developer.github.com/v3/activity/events/types/#milestoneevent
+type MilestoneEvent struct {
+	// Action is the action that was performed. Possible values are:
+	// "created", "closed", "opened", "edited", "deleted"
+	Action    *string    `json:"action,omitempty"`
+	Milestone *Milestone `json:"milestone,omitempty"`
+
+	// The following fields are only populated by Webhook events.
+	Changes *EditChange   `json:"changes,omitempty"`
+	Repo    *Repository   `json:"repository,omitempty"`
+	Sender  *User         `json:"sender,omitempty"`
+	Org     *Organization `json:"organization,omitempty"`
+}
+
 // PageBuildEvent represents an attempted build of a GitHub Pages site, whether
 // successful or not.
 // The Webhook event name is "page_build".

github/messages.go

@@ -49,8 +49,10 @@ var (
 		"integration_installation_repositories": "IntegrationInstallationRepositoriesEvent",
 		"issue_comment":                         "IssueCommentEvent",
 		"issues":                                "IssuesEvent",
+		"label":                                 "LabelEvent",
 		"member":                                "MemberEvent",
 		"membership":                            "MembershipEvent",
+		"milestone":                             "MilestoneEvent",
 		"page_build":                            "PageBuildEvent",
 		"public":                                "PublicEvent",
 		"pull_request_review_comment":           "PullRequestReviewCommentEvent",

github/messages_test.go

@@ -124,6 +124,10 @@ func TestParseWebHook(t *testing.T) {
 			payload:     &IssuesEvent{},
 			messageType: "issues",
 		},
+		{
+			payload:     &LabelEvent{},
+			messageType: "label",
+		},
 		{
 			payload:     &MemberEvent{},
 			messageType: "member",
@@ -132,6 +136,10 @@ func TestParseWebHook(t *testing.T) {
 			payload:     &MembershipEvent{},
 			messageType: "membership",
 		},
+		{
+			payload:     &MilestoneEvent{},
+			messageType: "milestone",
+		},
 		{
 			payload:     &PageBuildEvent{},
 			messageType: "page_build",