QuietHours: Change Logic (2/2)

Makes sense to me that turning QuietHours
    on should TURN QUIET HOURS ON with
    default time constraints applied.

I.E. QuietHours between 12:00am && 12:00am
    means QuietHours all day.  Having to
    adjust end time to 11:59 is redundant
    and not exactly the clearest implementation.
    Especially when we have a QuickToggle that
    directly toggles the setting on/off.

Change-Id: I8e77735fbfae8f2b730fab2bdbc38377ed7d720d