Nicer timestamps with momentjs

This dependency may be a little heavy for our current use case, but we can
roll with it for now and find something slimmer if it turns out yagni.

Closes #77
Closes #40

js/views/message_view.js

@@ -22,7 +22,7 @@ var Whisper = Whisper || {};
       this.$el.html(
         Mustache.render(this.template, {
           message: this.model.get('body'),
-          date: this.formatTimestamp(),
+          timestamp: moment(this.model.get('timestamp')).fromNow(),
           attachments: this.model.get('attachments'),
           bubble_class: this.model.get('type') === 'outgoing' ? 'sent' : 'incoming',
           sender: this.model.thread().get('type') === 'group' ? this.model.get('person') : ''
@@ -30,21 +30,8 @@ var Whisper = Whisper || {};
       );
 
       return this;
-    },
-
-    formatTimestamp: function() {
-      var timestamp = this.model.get('timestamp');
-      var now = new Date().getTime();
-      var date = new Date();
-      date.setTime(timestamp*1000);
-      if (now - timestamp > 60*60*24*7) {
-        return date.toLocaleDateString('en-US',{month: 'short', day: 'numeric'});
-      }
-      if (now - timestamp > 60*60*24) {
-        return date.toLocaleDateString('en-US',{weekday: 'short'});
-      }
-      return date.toTimeString();
     }
+
   });
 
 })();