Revert "Revert "Remove cm clear all button [1/2]""

This reverts commit 122df03b28f2ef0aff567263b1e5cb477246545f.
Revert "Remove PA Clear all button"

This reverts commit 0282a0da6b7a8c25313886cd208a8a59501e96e0.
Revert "Better clear all recents drawables"

This reverts commit bfa5cfb1813ca43c80aad56286b2db5293b43958.
Use 'dismissAllTasks' to clear all apps
make switch to last app animation snappier

Change-Id: Ia253a3db45109da7dd4f7a2467184d81c04918b4
Framework: add Settings.System boolean helper methods

Conflicts:
	core/java/android/provider/Settings.java
Framework: Add enabler for Navbar Recents

Conflicts:
	core/java/android/provider/Settings.java