Squash of clear all recents position toggle+

ported to vanir and changed to use a single settings constant

PS2: rebase

commit 7b980c1ba1356c239a374da8a9468b2998146b27
Author: benjamingoodwin <benjamin.j.goodwin@gmail.com>
Date:   Sun Nov 17 18:33:32 2013 +0530

    Clear All button added in  Recent Panelview.

    Ref: https://github.com/temasek/android_frameworks_base/commit/a129580ee886b48c124de716236c2bae2b93a77b

    PS3: capability to show/hide based on setting added

    Change-Id: Iab4db7abec6f8caee4c0faad0960fa0f9fb9a1fd
    PS6: capability to change button layout_gravity

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

    Change-Id: Iedb938cf2b6ca6f264429c6ccafab72944c73d98

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

commit ee27029a1e3feb62c7238bf263444d8d8b29b5f9
Author: PrimeDirective <activethrasher00@gmail.com>
Date:   Sat Feb 8 13:59:58 2014 -0500

    Revert ""Clear all" button on recent apps"

    This reverts commit 6471aee7bec8e8d2eb179db9605d3b6a12ac48f6.

    Conflicts:
    	packages/SystemUI/res/layout-land/status_bar_recent_panel.xml
    	packages/SystemUI/res/layout/status_bar_recent_panel.xml

    Change-Id: I12efcfae2919df9ee8d4d5669ccca64eb627e64b

Change-Id: Ied4beb00adb58f90df3b131249cf409f8f2b9757