PLT-2241 Refactored statuses into a more real-time system (#3573)

* Refactored statuses into a more real-time system

* Updated package.json with correct commit and fixed minor bug

* Minor updates to statuses based on feedback

* When setting status online, update only LastActivityAt if status already exists

webapp/utils/constants.jsx

@@ -191,7 +191,8 @@ export const Constants = {
         USER_REMOVED: 'user_removed',
         TYPING: 'typing',
         PREFERENCE_CHANGED: 'preference_changed',
-        EPHEMERAL_MESSAGE: 'ephemeral_message'
+        EPHEMERAL_MESSAGE: 'ephemeral_message',
+        STATUS_CHANGED: 'status_change'
     },
 
     UserUpdateEvents: {
@@ -210,6 +211,12 @@ export const Constants = {
         POST: 5
     },
 
+    UserStatuses: {
+        OFFLINE: 'offline',
+        AWAY: 'away',
+        ONLINE: 'online'
+    },
+
     SPECIAL_MENTIONS: ['all', 'channel'],
     CHARACTER_LIMIT: 4000,
     IMAGE_TYPES: ['jpg', 'gif', 'bmp', 'png', 'jpeg'],