Check that SimulatorBridge is READY before using it
Check that SimulatorBridge is READY before using it

Summary:
Finding some crashes related to the mach port not being registered.

Fortunately the SimulatorBridge executable outputs "READY" in it's main, after it's set up the mach ports. This would explain race conditions in the start up that relates to the SimulatorBridge object not working

Reviewed By: c-ryan747

Differential Revision: D21739701

fbshipit-source-id: 03593c0fdee884ced76231a30f90ccc50c36e11d

facebook/FBSimulatorControl,facebook/FBSimulatorControl,facebook/FBSimulatorControl,facebook/FBSimulatorControl,facebook/FBSimulatorControl