Add QS GPS Tile [2/2]

* This patch adds a quick settings tile to control GPS (not location, just plain GPS signal). Basically it allows the user to switch between "high accuracy" (high battery consumption) and "battery saving". The other location tile only allows the user to turn location completely on or off, but it doesn't allow control over the location mode.

* The tile will also keep track if location is turned off, or if the gps/location settings are changed from the Android settings.

Change-Id: I2431a224b8de12301e79d422e51dbfa928bb0248