policy: always use hardware acceleration for keyguard

Without hardware acceleration, keyguard widget will appear aliased
and choppy (especially at the end of the scroll).

Change-Id: I1bfb6fbcba6306edf366e8ea752d6919936c3ab6
Make system layout fill the window properly on expanded desktop mode

This commit fixes e.g. the gap on the bottom of the lock screen
or the gap on the right side of status bar on landscape mode.

Patch set 2  : Remove whitespace issues
Patch set 3  : Code cleanup
Patch set 4  : Damn whitespace errors

Change-Id: Ic8a6b748f94d7dcc883201579d199898713c90fd
Lockscreen Targets: Icon Revamp

Adjust the size of custom app icons and resize and round the corners
of gallery icons for a more uniform look.

Before http://imgur.com/cTOqdwX

After http://imgur.com/EKAeFiw

Change-Id: Ibcca275eb0ae946775773a8c8217b6508da10e5b
SystemUI: allow update Mobile Network Type tile display

For the moment, this tile is only updated when clicking on it.
With these changes we have the same behavior as the other tiles:
if setting is changed in system settings, Mobile Network Type tile
display is updated.

    * Patch Set 1: Initial commit
    * Patch Set 2: Some corrections, commit message changed

Change-Id: I6cadadf4b9e3c9f478a4286e26d657da4f3ff015