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: provide disable method to support system themes - primedirective
PS4: flip boolean to "enable" custom colors to appease some OCD and remain
     consistent throught the color settings in the ROM

NUCLEARMISTAKE WAZ HERE
PS8: Actually remove the "reset colors" functionality
     !Overriden ==> Custom... because a checked box == true, not false...
         and because having opposite boolean logic in settings from frameworks to
         simulate correctly designing a toggle feature is the WRONG WAY to do it.

Change-Id: I19b12a8cd6c1958a3b0a3c8104c913c184734778