QS: Update heads up tile icons

The bell icon for the "on" state look a bit crappy.
Update them too look more lika a bell.

Screenshot: http://goo.gl/rC1VFD

Change-Id: I9a6a54a5ee9ac0100ebf749ee3babe02eb0e2e32
Merge pull request #13 from CyanogenMod/cm-11.0

QS: Update heads up tile icons