PowerManager : Make proximity check opt-in

Change-Id: I7cf64a82530da2e655018e43683ba7a5584d54f8

Conflicts:
	core/res/res/values/config.xml
	core/res/res/values/symbols.xml
	services/java/com/android/server/power/PowerManagerService.java

Conflicts:
	core/res/res/values/config.xml
	services/java/com/android/server/power/PowerManagerService.java