Merge pull request #239 from nickago/MM-1295

MM-1295 Removal from a channel occurs in real time

model/message.go

@@ -16,6 +16,7 @@ const (
 	ACTION_VIEWED       = "viewed"
 	ACTION_NEW_USER     = "new_user"
 	ACTION_USER_ADDED   = "user_added"
+	ACTION_USER_REMOVED = "user_removed"
 )
 
 type Message struct {