SlimActions: add new actions and cleanup

A bit cleanup.

As well add 4 actions:

- camera intent
- play/pause music
- next music track
- prev music track
- wake up device

As well check for system ready on the other audio actions which are already present.

ToDo: One of the rare classes which are very bad documented. We need to add code comments
ASAP

Change-Id: Ib327b39fbd709c6b77fca5febe97712348937c40

Conflicts:
	core/java/com/android/internal/util/slim/ButtonsConstants.java
	core/java/com/android/internal/util/slim/SlimActions.java
HeadsUp: option to launch in floating window (1/2)

Conflicts:
	packages/SystemUI/src/com/android/systemui/statusbar/notification/NotificationHelper.java

Change-Id: I1721e3fc8cf385cd4d90f407f882830dd29d58b8