[1/2] Frameworks: Lockscreen Blur

- If user selects "Translucent blur" under screen security,
  the locksceen background will now appear transparent
  with the content behind it blurred.

Modificaitons made to the orginal commit to support Hammerhead and Flo.
It seems full HD images causes rendering artifacts. To prevent this,
we scale the image size to something more manageable.

PS2: Reduce calls to System.Settngs
     Move bitmap scaling to DisplayPowerController
PS3: Fix styling

Change-Id: Ie72bab697726af5e145bd0192980885ea7222ecd

Conflicts:

	services/java/com/android/server/power/DisplayPowerController.java