GlobalActions: Fix setting ringer mode in global actions

It looks like we did not bring in this full feature for cm-13.0.
This patch updates SilentModeTriStateAction to match cm-12.1 with
one minor change.  We can no longer set the zen mode by writing to
Global settings directly.  The ZenModeHelper class actually checks
when a change is made and resets it.  The fix is to use
INotificationManager.setZenMode() instead.

Change-Id: Ib2423a19da3a2ca95f73cb92247e0a38bff8bbee
TICKET: CYNGNOS-1808