Never remove Timer times up notification.

Bug: 23709019
Bug: 23707132
Bug: 23478562

Timer times up notification used to hide/show depending on app
open state. Now firing timer notifications are never hidden.
This is consistent with firing Alarm notifications.

Add call to re-sync UI on timer stop action in case the HUN stop is
clicked while on TimerFragment.

Change-Id: I69276246ed2c6136f5424a0db28c882d1d625d30