title: PushPlugin is not working after upgrading to cordova 3.1.0
body: <p>After Cordova upgrading to 3.1.0, onNotificationGCM function event = register cannot been called. So I can get push notification for the registered phone, but new phone cannot be registered.</p>
  
  <p>Checking console of ATD, I got this:</p>
  
  <pre><code>W/PluginManager(31200): THREAD WARNING: exec() call to PushPlugin.
  register blocked the main thread for 30ms. Plugin should use
  CordovaInterface.getThreadPool().
  </code></pre>
  
  <p>Anyone has same problem and could give some suggestions on this?</p>