SystemUI: StayAwake Toggle

Instead of overcomplicating toggle, onLongClick simply takes the user to
Settings$DisplaySettingsActivity instead. onClick (on) sets screen
timeout to
int MAX_VALUE(approx 24 days), and restores user value onClick (off).

** Icon Credit to Nitroz(Thanks a ton!)

Change-Id: Ifd2051b2a6e8235160713cad3b4385dbb6d66b8f
Signed-off-by: bmc08gt <bmc08gt.teamb00sted@gmail.com>