Print success in shell mode
Print success in shell mode

Summary: More ergonomic than having to call `last_success` after each command

Reviewed By: lawrencelomax

Differential Revision: D26422499

fbshipit-source-id: 0161796c332c50ae5da3ade8c0835a8e2fded03f

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