Settings: Heads up meets SlimKat....SlimKat meets Google IO [4/4]

**Orignal commit can be found here:
https://github.com/SlimRoms/packages_apps_Settings/commit/b5eacf0b6a89b8531cbbb8693ec2e096d719eeba

For detailed explanation see here: https://gerrit.slimroms.net/#/c/9937/

This patch adds the 4 possible user configurable settings.

1. Enable always expanded heads up notifications.
2. Set heads up snooze time
3. Set timout timer
4. Show updates of pending notifications

5. Add in app info screen a checkbox to enable heads up for the app.
   As another possibility aside the longpress on the notification on
   notification drawer.

Change-Id: I999df799cecb487c502e4a77626445813eeb197f

Conflicts:
	res/values/mahdi_arrays.xml
	res/values/mahdi_strings.xml