Settings: AdaptiveBacklight support

Add support for adaptive backlight technologies like NVIDIA SmartDimmer, QCOM CABL or Samsung CABC.

Patchset 2: Use internal shared prefs to store the smardimmer setting
Patchset 3: Rename to AdaptiveBacklight
Patchset 4: Reorganize settings and strings to follow design guidelines
Patchset 5: CleanUp
Patchset 6: Added suggestions
Patchset 7: Sync default value. CleanUp.

Depends	on http://review.cyanogenmod.org/#/c/48465/

Change-Id: Ib0e05770bf90b664a00e65f46d32cc9a07be1377
Signed-off-by: Jorge Ruesga <jorge@ruesga.com>