Fix busy-wait loop in DashboardFragment

[kalynstricklin]

This is a busy-wait with no timeout waiting for the SensorHub init and can block the UI thread or 'wait' indefinitely.

  while (service.getSensorHub() == null) {
      System.out.println("Waiting for BoundService Hub to start...");                                                                        
  }                                                                                                                                          
  while (service.getSensorHub().getEventBus() == null) {                                                                                     
      System.out.println("Waiting for BoundService Hub EventBus to start...");                                                               
  }

• The print statements spams logcat, and there is not really anything happening if osh fails to initialize. this is bad code. Replace with callback/listener instead or something to handle this situation more gracefully.