Settings: 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: I75f3656ae5b4ac4a4bd1c1cbed6c07ab2863f4fd
Merge "Settings: Lockscreen Targets Icon Revamp" into cm-10.1