CFX hardware key action implementation (2 of 2)

Based upon the work @CyanogenMod did with Home key, we
dramatically expanded the concept. Any action can be applied to
any available key's single tap, double tap, and long press events
with the following exceptions:

Back key single tap always executes a Back action
Home key single tap always executes a Home action

For safety, security, and sanity, these are static and can never
be changed. We don't use any cyanogenmod uri's to store values so
if the user changes roms, those values are preserved. We apply common
sane default values to all devices.