Add a guard around iOS Sim usage with instructions to users about how to install node and ios-sim
Add a guard around iOS Sim usage with instructions to users about how to install node and ios-sim

paulstringer/OCSlimProject,paulstringer/OCSlimProject,ncoelle/Slim-iOS-TestRunner,ncoelle/Slim-iOS-TestRunner,paulstringer/OCSlimProject,paulstringer/OCSlimProject,ncoelle/Slim-iOS-TestRunner,ncoelle/Slim-iOS-TestRunner