VolumePanel: Rework design on top of Hover

Signed-off-by: David L.-W. <xD_e-mail@gmx.de>

Conflicts:
	core/java/android/view/VolumePanel.java
	packages/SystemUI/src/com/android/systemui/statusbar/notification/Hover.java

Conflicts:
	core/java/android/view/VolumePanel.java
	core/res/res/values/colors.xml
	packages/SystemUI/src/com/android/systemui/statusbar/phone/PhoneStatusBar.java