apps/settings: Add auto/manual brightness control to Brightness settings

apps/settings: Add auto/manual brightness control to Brightness settings

Add changes to have the ability to turn on and off the
automatic light sensing for the device.  This is fully configurable
and is by default not  present.  Vendors should override the ALS setting
to enable the automatic lighting controls.

These changes will add a check box to the Brightness settings menu to give control
to the user to allow the device's display lighting to be controlled via the slide bar
or the auto lighting system.

If the user selects auto then the slide bar will become invisible.  Manual mode
will present the slide bar to the user.

Change-Id: I512c9d5dd72ddd831b33eb8fcd4680e2fc7f786e
Signed-off-by: Dan Murphy <D.Murphy@motorola.com>
Signed-off-by: Mike Lockwood <lockwood@android.com>