title: How to get click listener of push notification in IONIC2
body: <p>I am working with following plugins for receive GCM push notifications.
   ionic plugin add phonegap-plugin-push 
   install --save @ionic/cloud-angular</p>
  
  <p>I got success for receive the push notification, but not able to set click listener.</p>
  
  <p>How to set click listener of notification?</p>
  
  <p>Please help me if anybody know regarding push notification handling using IONIC2.</p>