base: Add battery level around unlock handle [1/2]

PS2:
added missing change in KeyguardSelectorView.java

Change-Id: Ia4dbc2335657c096c34349ec67c4adfec0aeb91b

Conflicts:
	core/java/android/provider/Settings.java
	packages/Keyguard/src/com/android/keyguard/KeyguardSelectorView.java