boardconfig: import TWRP flags from SlimKat tree
boardconfig: attempt to mount cache before reboot.

-Should fix reboot in recovery.
boardconfig: Add brightness path for PhilZ
boardconfig: More twrp build flags.
boardconfig: mount cache before reboot.

-Need to make sure that cache is mounted before we write there.
init: allow voltage changes.

-Set permissions on sysfs interface paths for cpu frequency
voltages.
recovery: adopt TWRP's generic gr_text implementation.

-This works for CWM, PhilZ and TWRP because the
ellipses allows a variable number of parameters in the
function prototype.