ipad_keyboard_mode will now raise an error if called when device is not an ipad
replaced iphone? device checks in keyboard_helpers with
device_family_iphone? because calabash supports testing on ipods
keyboard_enter_char 'Delete' now works on iOS 6 + UIA
Merge pull request #276 from jmoody/0.9.x-more-keyboard

fixes keyboard_enter_char 'Delete' on iOS 6 + Instruments