Add iOS7 Controller Support

Added support for iOS7 Wired Controllers (such as Moga Ace Power and Logitech Powershell). 

A couple notes:
- Tested on Logitech Powershell.
- iOS 6 and earlier supported versions should still work. (Tested iOS 6 only)
- Will work with already connected controllers or ones plugged in during runtime.
- Will hide onscreen controls when controller is detected.
- Will disable idle (sleep) timer when controller is detected. Oddly, controller input does not reset the idle timer so this was necessary.
- May work with iOS7 wireless controllers that are already connected, however did not add ability to search for and connect new wireless controllers from within application.
- There may be issues with the way d-pad handling works on controllers with analog input due to not accounting for a dead zone. This may already be handled internally by the GCController API so I didn't try to guess it. Need to test on Moga Ace Power.