Notification count overlay over status bar icon

From omnirom: https://github.com/omnirom/android_packages_apps_OmniGears/commit/c5d09ba9275951e971d7cf5f2eabf373777f1a45

Changes made for it to fit in slim.

Change-Id: I1b84e1e448b12919e1606969c76a108ad6157d9b

Conflicts:
	res/xml/status_bar_settings.xml
	src/com/android/settings/slim/StatusBar.java