SystemUI: animate transparency changes

Change-Id: I597b245b2d98ae42118efc1ba7ccb837edfdbea9
Signed-off-by: Roman Birg <romanbirg@gmail.com>

Conflicts:
	core/java/com/android/internal/util/aokp/BackgroundAlphaColorDrawable.java
	packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBarView.java