NavigationBar: Custom height (1/2)

Ported from http://review.cyanogenmod.org/#/c/23609/

Change-Id: I61aef192ac658f54f86b87d18cce9d7b073004e2

Conflicts:
	policy/src/com/android/internal/policy/impl/PhoneWindowManager.java

Conflicts:
	policy/src/com/android/internal/policy/impl/PhoneWindowManager.java