title: How to send actionable notifications to iOS with FireBase?
body: <p>We are currently evaluating Firebase as a future push notification service.
  Is there a way to send actionable notifications to iOS devices? 
  At the moment we use parse to send pushes, we set the "category" parameter in the payload and the additional actions on the notifications are working.
  We tried to set this parameter in the firebase console or via the firebase rest api, but the notification actions are not working, it seems the payload is somehow different then iOS expects.</p>