title: cordova push plugin callback not invoked when the app is in background
body: <p>I have the push plugin <a href="https://github.com/phonegap-build/PushPlugin.git" rel="noreferrer">https://github.com/phonegap-build/PushPlugin.git</a> 
  configured with cordova 3.5. When the app is in foreground, the notification plugins callback is invoked and everything works as expected.</p>
  
  <p>When the app is inactive(in the background), the notifications are received and i can see them in the notification bar but the callback function is not invoked. My code is based on the example given in push plugin. Below is my code simplified to reproduce the issue,</p>
  
  <pre><code> initialize : function () {
      console.info('NOTIFY  Ready to register for push notification.');
      var pushNotification = window.plugins.pushNotification;
      // Register device with push server
      pushNotification.register(gcmSuccessHandler, gcmErrorHandler, {
            'senderID': GCM_SENDER_ID,
            'ecb': 'onNotificationGCM'
       });
  
   }
  
  window.onNotificationGCM = function(notification){ 
      //the beep is invoked 3 times only when the app is in foreground
  navigator.notification.beep(3);
      console.log('EVENT -&gt; RECEIVED:' + notification.event + '');
  
  }
  </code></pre>
  
  <p>I have been breaking my head on this issue for over a day. Any help is appreciated.</p>
  
  <p><strong>UPDATE:</strong>
  I finally found what the issue was. I had to clear the dalvik cache and restart my phone. Happened to me twice so far. Seems to a known issue in android, <a href="https://github.com/phonegap-build/PushPlugin/issues/35" rel="noreferrer">https://github.com/phonegap-build/PushPlugin/issues/35</a>.</p>