transparent nav bar

Signed-off-by: Roman Birg <romanbirg@gmail.com>
Change-Id: I71eb46af407ec97084dcf7944f0c4231c98dbe97

Conflicts:

	packages/SystemUI/res/layout-sw600dp/navigation_bar.xml
	packages/SystemUI/src/com/android/systemui/statusbar/NavigationBarView.java

Signed-off-by: iceandfire <arhamjamal@gmail.com>