Settings: Notification Shortcuts [2/2]

Patchset 2: Added hide carrier label toggle, added multi-user support,
fixed whitespace, cleanup of code.

PS2: Rebase

Change-Id: I33e510da1885bc5bcdfbda6b5b4eec6cb1a3a654
Signed-off-by: STELIX <ssspinni@gmail.com>