"Clear all" button on recent apps

Completly rewritten to be more aosp like (Check keyboard as example)
An icon will appear on navbar when apps available to be killed

Change-Id: Iceb86eef41160f1c17e51463b37fd97e27acfb2e

Conflicts:
	packages/SystemUI/res/layout-port/status_bar_recent_panel.xml
	packages/SystemUI/src/com/android/systemui/recent/RecentsPanelView.java

Conflicts:
	packages/SystemUI/src/com/android/systemui/recent/RecentsPanelView.java
	packages/SystemUI/src/com/android/systemui/statusbar/BaseStatusBar.java
	packages/SystemUI/src/com/android/systemui/statusbar/phone/NavigationBarView.java