power: Add panel auto-brightness configuration

 * Some panel hardware requires that we twiddle some knobs in sysfs to
   enable proper display calibration (gamma, etc) when auto-brightness
   is enabled. Add a configuration value to handle this.

Change-Id: I3c793c3520fc6f9a18d5a3abf1fe0df803c5e580
PackageManager: allow build-time disabling of components

Allow components to be specified as disabled at build time
(applied on boot).

This allows stock OTA components to be marked as disabled in
CM builds.

Change-Id: I6e4499cc40a779792a5ea97a10137399dad7d69f

Conflicts:

	core/res/res/values/symbols.xml