Added iCade support to the iOS Build

I've added in iCade support for the iOS build.  I have an iCade 8-bitty that I used to test with on both an iPad 3 and iPhone 5.  I've mapped the four buttons like so:

[] /\
X O

Double-pressing the Select button within 1 second will switch the DPad between normal DPad operation and simulating the Analog Stick (so you can navigate menus, then switch to driving a car, eg.).

I don't have one of the bigger iCade cabinets to test with, but I believe the buttons would be mapped like this:

L R [] /\
Select Start X O

Supposedly the Gametel controller emulates an iCade controller, and the iControlPad controller can emulate an iCade controller too, so those might work as well, though the buttons may be mapped wrong.