Add --device-type arguments to cli test runner
Add --device-type arguments to cli test runner

Summary: We run all cli tests against 'iPad Air 2' and 'iPhone 6', but this is mostly unecessary by default. Sets the default to only run against 'iPhone 6' but multiple device types can be run against by adding the '--device-type' param.

Reviewed By: asm89

Differential Revision: D4037464

fbshipit-source-id: 2fde59b44b2efaec9198b6e1987a3b22dd934ae8

ichu501/FBSimulatorControl,facebook/FBSimulatorControl,StevenUpForever/FBSimulatorControl,StevenUpForever/FBSimulatorControl,plu/FBSimulatorControl,facebook/FBSimulatorControl,plu/FBSimulatorControl,plu/FBSimulatorControl,StevenUpForever/FBSimulatorControl,facebook/FBSimulatorControl,plu/FBSimulatorControl,facebook/FBSimulatorControl,StevenUpForever/FBSimulatorControl,facebook/FBSimulatorControl