Frameworks: reduce SlimPie observer footprint (1/2)

time for code cleanup projects. Switch to same
logic we already use in QS/NT shortcuts. Use
only one string for the whole SlimPie config
This reduces massive the observer footprint.

cheers

Change-Id: I884c5d25c682e06d6649a16c2ba6d84460a3776f

Conflicts:
	core/java/android/provider/Settings.java