Update and de-scrub lockscreen wallpaper

Do I look like your mother? Then clean up after your damn self.

1. Use WallpaperCropper + WallpaperManager to handle backgrounds
2. Get rid of "style" enumeration - its values were defined independtly, everywhere it was used, it was numbered with 2 being the default
   and it was probably determined to be necessary after COMPLETELY neglecting to decompose the problem it was used to solve.
   - Default (same as launcher) == chose "clear" in the picker
   - Custom == pick a wallpaper in the picker
   - Transparent == check the box (supercedes default/custom background and disables the setting for it)
   - Blurry == duh (only enabled when transparent)
3. Kill the lockscreen background colorpicker
   - Anyone who misses manually setting solid color background is an idiot.
     Idiots daily-drive windows (but not all windows daily-drivers are idiots :=P), and therefore can make their own solid color background in mspaint without rebooting.
4. Clean up a plethora of egregeous acts committed previously
   - An apparent intentional disuse of compound boolean expressions
   - Unnecessary imports
   - Back-asswards ListView handling
   - War crimes

Change-Id: I096695a6f345d16871f2967ebbba74d6ca961448