Battery level: customizable icon and text

Squashed commits from Slimsaber (original code by @kecinzer)
This also revert the native android battery in-icon percentage
commit.

Change-Id: I5affd3d81ead9a0a395e3dfc11db37cc0dc10433
Battery style: fix dynamic percentage setting

not being disabled after escaping from the statusbar
settings page and going back to it
(bug reported here: http://review.cyanogenmod.org/#/c/82420/)

Change-Id: I8a39fbf1b1d032065714dfe0bcfa940816513198