DRY up PushMessageContentProtobuf construction

Messages now know how to protobuf-ify themselves.

js/models/messages.js

@@ -3,29 +3,38 @@ var Whisper = Whisper || {};
 (function () {
   'use strict';
 
-  var Message  = Backbone.Model.extend();
+  var Message  = Backbone.Model.extend({
+    toProto: function() {
+      return new PushMessageContentProtobuf({body: this.get('body')});
+    }
+  });
+
   Whisper.Messages = new (Backbone.Collection.extend({
     localStorage: new Backbone.LocalStorage("Messages"),
     model: Message,
     comparator: 'timestamp',
 
     addIncomingMessage: function(decrypted) {
-      Whisper.Messages.add({
+      var m = Whisper.Messages.add({
         person: decrypted.pushMessage.source,
         group: decrypted.message.group,
         body: decrypted.message.body,
         type: 'incoming',
         timestamp: decrypted.message.timestamp
-      }).save();
+      });
+      m.save();
+      return m;
     },
 
-    addOutgoingMessage: function(messageProto, recipients) {
-      Whisper.Messages.add({
+    addOutgoingMessage: function(message, recipients) {
+      var m = Whisper.Messages.add({
         person: recipients[0], // TODO: groups
-        body: messageProto.body,
+        body: message,
         type: 'outgoing',
         timestamp: new Date().getTime()
-      }).save();
+      });
+      m.save();
+      return m;
     }
   }))();