title: Receive message when push notification is disable
body: <p>In order to let server send mobile app client a message,</p>
  
  <p>I want to use push notification.</p>
  
  <p>But if user disable the app notification, the message cannot be received.</p>
  
  <p>Can i do something to receive push notification message in the app?</p>
  
  <p>Or other method can let server send a message to mobile app?</p>
  
  <p>My development environment : Unity3D, OneSignal(Push notification Library), LNMP </p>