OmniSwitch: bugfixes and improvements

-added app drawer with flip animation
-added BitmapCache
-debounce glow selector
-settings button change
 -short press opens global settings
 -long press opens app settings
-preload recents on drag handle down event
-fix handling of long press button events
-change overlay background handling
-add whole screen background dimming option
-added permission check on service start

Change-Id: Ia9e55887aa7c73bae6fc1d55e32d6613c605edc1