Don't require a conversation name

Just display a sensible default in the frontend if it's unset.
For private conversations this should be the phone number, for
groups, the list of numbers.

js/background.js

@@ -141,7 +141,6 @@
                     };
                 } else {
                     attributes = {
-                        name       : source,
                         type       : 'private'
                     };
                 }

js/models/conversations.js

@@ -24,7 +24,6 @@
     defaults: function() {
       var timestamp = new Date().getTime();
       return {
-        name        : 'New Conversation',
         image       : '/images/default.png',
         unreadCount : 0,
         timestamp   : timestamp,
@@ -37,7 +36,7 @@
     },
 
     validate: function(attributes, options) {
-      var required = ['type', 'timestamp', 'image', 'name'];
+      var required = ['type', 'timestamp', 'image'];
       var missing = _.filter(required, function(attr) { return !attributes[attr]; });
       if (missing.length) { return "Conversation must have " + missing; }
     },

js/views/conversation_list_item_view.js

@@ -31,7 +31,7 @@ var Whisper = Whisper || {};
     render: function() {
       this.$el.html(
         Mustache.render(this.template, {
-          contact_name: this.model.get('name'),
+          contact_name: this.model.get('name') || this.model.get('members') || this.model.id,
           contact_avatar: this.model.get('image'),
           last_message: this.model.get('lastMessage'),
           last_message_timestamp: moment(this.model.get('timestamp')).format('MMM D')