title: PushNotificationIOS.requestPermissions() callback
body: <p>I don't want to ask my users to allow notifications before they actually need them in the app.</p>
  
  <p>So when a user schedules a local notification in my app I want to request notification permissions and if the user accepts then set the local notification.
  The problem is that there doesn't seem to be any callback for <code>PushNotificationIOS.requestPermissions()</code>, meaning that if I call <code>PushNotificationIOS.checkPermissions()</code> right after it will run before the user has tabbed the alert window and return <code>0</code> in the permissions object, even though the user might accept.</p>
  
  <p>So my question is if there is any way to request permissions and subsequently set a notification, or do I have to request permissions before I actually need to use them?</p>