"Clear all" button on recent apps

Port forward from cm-10.2

Change-Id: I9ebcf22f85957f61caefb14e0efd4cf2978d92cd

Conflicts:
	packages/SystemUI/res/layout-land/status_bar_recent_panel.xml
	packages/SystemUI/res/layout/status_bar_recent_panel.xml
	packages/SystemUI/src/com/android/systemui/recent/RecentsHorizontalScrollView.java
	packages/SystemUI/src/com/android/systemui/recent/RecentsVerticalScrollView.java

Clear all recents button cleanUp
reference https://github.com/CyanogenMod/android_frameworks_base/commit/6471aee7bec8e8d2eb179db9605d3b6a12ac48f6

Conflicts:
	packages/SystemUI/src/com/android/systemui/recent/RecentsHorizontalScrollView.java
	packages/SystemUI/src/com/android/systemui/recent/RecentsVerticalScrollView.java