Fix message view using the wrong attribute

js/views/message_view.js

@@ -75,7 +75,7 @@
             message: this.model.get('body'),
             timestamp: moment(this.model.get('received_at')).fromNow(),
             bubble_class: this.model.get('type') === 'outgoing' ? 'sent' : 'incoming',
-            sender: this.model.get('sender')
+            sender: this.model.get('source')
           })
         );