Remove spurious update to conversation on delivery receipts

Previously this would trigger the conversation to refresh it's last
message.

// FREEBIE

js/delivery_receipts.js

@@ -69,7 +69,7 @@
                             message.get('conversationId')
                         );
                         if (conversation) {
-                            conversation.trigger('newmessage', message);
+                            conversation.trigger('delivered', message);
                         }
                     });
                     // TODO: consider keeping a list of numbers we've

js/views/conversation_view.js

@@ -80,6 +80,7 @@
             this.listenTo(this.model, 'change:color', this.updateColor);
             this.listenTo(this.model, 'change:name', this.updateTitle);
             this.listenTo(this.model, 'newmessage', this.addMessage);
+            this.listenTo(this.model, 'delivered', this.updateMessage);
             this.listenTo(this.model, 'opened', this.onOpened);
             this.listenTo(this.model, 'expired', this.onExpired);
             this.listenTo(this.model.messageCollection, 'expired', this.onExpiredCollection);
@@ -237,6 +238,9 @@
                 this.markRead();
             }
         },
+        updateMessage: function(message) {
+            this.model.messageCollection.add(message, {merge: true});
+        },
 
         viewMembers: function() {
             return this.model.fetchContacts().then(function() {