Base: App Circle sidebar (add support floating window)

PS.8 : rebased
PS.9 : add support minimize/maximize window
PS10 : rebased

Change-Id: Ied388a0a4054dfaf1d3e6fcdc33dd5aab28565a9

Conflicts:
	packages/SystemUI/res/menu/sidebar_popup_menu.xml
	packages/SystemUI/res/values/custom_strings.xml
	packages/SystemUI/src/com/android/systemui/appcirclesidebar/AppCircleSidebar.java