Port "immersive mode"

Credits to chameleon OS

Conflicts:
	core/res/res/values/symbols.xml
	policy/src/com/android/internal/policy/impl/GlobalActions.java
	policy/src/com/android/internal/policy/impl/PhoneWindowManager.java
Revert "Port "immersive mode""

This reverts commit c6008a6db81ccf99a37929801336b345fceade15.