Add circle gear to display options [2/2]

PS1:  Fixed whitespaces and tabs
PS3:  Resized hdpi icons to 27 pixels
ps4:  for x in `find packages/apps/SystemUI/res/ -name '*.png'`; do optipng -nc -nb -o7 $x; done

Change-Id: I46c4baa636ecc09b80f85fbb667a2228e4551536