frameworks/base: Update quick launch shortcut icons/resources

Update the existing icons and add "xxhdpi" versions created
from a vector template. This commit cleans also the resource
files a bit up.

Screenshot: http://goo.gl/6CrMYr

Conflicts:
	core/java/com/android/internal/util/cm/NavigationRingHelpers.java

Change-Id: I45abee5cf13cd239eb5b4402019afac28d6d5952