Settings: Slimrecents background color && transparency [1/2]

Allow user to specify background color and transparency level for the slimrecents panel.

Change-Id: I6771a5b700b541e630c6d83e4427030fa83d34ea

Conflicts:
	res/values/ose_strings.xml
	res/xml/recent_panel_settings.xml
	src/com/android/settings/liquid/RecentPanelSettings.java