title: PushSharp - GCM Authorization Failed
body: <p>Using v4.0.10 of Pushsharp (nuget package), I am getting error <code>GCM Authorization Failed</code> when sending push notifications to Android devices.</p>
  
  <p>Seems the bug raised in issue 574 (<a href="https://github.com/Redth/PushSharp/issues/574" rel="nofollow noreferrer">https://github.com/Redth/PushSharp/issues/574</a> ) has been compiled into the nuget package, yet I'm still getting this error.</p>
  
  <p>Could this be related to the introduction of Firebase Cloud Messaging?</p>
  
  <p>Does anyone still have success using GCM?</p>