title: Spotify JavaScript API song end/start events with the new API
body: <p>Is there any way to listen to events on track end, current time and track start with the new Spotify Api. </p>
  
  <p>I have the following code</p>
  
  <pre><code>models.player.observe(models.EVENT.CHANGE, function(
    console.debug(event);                
  });
  </code></pre>
  
  <p>But, returns an error with "Cannot read property 'CHANGE' of undefined". 
  And of course the observer is called within require(...models ...)</p>
  
  <p>Can anybody help?</p>