QS tiles background mod.[2/2]

Option to set the color of QS background
and the color when pressed.

PS2: enable the alpha slider
PS3: move flip tiles to styles
Change-Id: Iee74a821df84a85772a3f8edbecaf234fad83bb2

Conflicts:
	res/values/strings.xml
	res/xml/quicksettings_tiles_style.xml
	src/com/android/settings/quicksettings/QuickSettingsTilesStyle.java

Change-Id: I88d614a25a2373ba85f62b0e4f81e3e4281e0782
Merge "QS tiles background mod.[2/2]" into kk44