title: Backbone collection.add is not working
body: <p>I have a pretty basic setup like this:</p>
  
  <pre><code>var MusicModel = Backbone.Model.extend({});
  var PlaylistCollection = Backbone.Collection.extend({
      model: MusicModel,
      events: {'add':'add'},
      add: function(mdl){
          //This is working perfectly fine even output of model
          console.log(mdl);
      }
  });
  
  var playlistCollection = new PlaylistCollection();
  playlistCollection.add(new Music(data));
  </code></pre>
  
  <p>The model is not actually added to the collection. If I try to use Chrome console and enter <code>playlistCollection.length</code> it will output 0 and <code>playlistCollection.models</code> will output <code>[]</code>.</p>
  
  <p>Any idea what I am doing wrong?</p>