Handle missing simulator OS versions

[interstateone]

If FBSimulatorControl doesn't have new OS versions defined yet, the list of simulators will be incorrect. There are two things that need to change here:

• Make sure that if FBSimulatorControl provides an empty list of simulators that the menu represents that instead of showing bogus menu items 8266cd
• Notify the user that this is the case, because there won't be anything they can do to run a playground