Send room ID in http notifications so clients know which room to go to if the...

Send room ID in http notifications so clients know which room to go to if the user responds to the notification.

synapse/push/httppusher.py

@@ -66,6 +66,7 @@ class HttpPusher(Pusher):
         d = {
             'notification': {
                 'id': event['event_id'],
+                'room_id': event['room_id'],
                 'type': event['type'],
                 'sender': event['user_id'],
                 'counts': {  # -- we don't mark messages as read yet so