Fix bug #3098972 (event notifications may not fire on time)

- aggregate scheduling of next alarm checks for 5s
- use the AlarmService for controlling when to do the checks
- suppress the AlarmScheduler threads
- use a Service and trampoline for running the next alarm check

Change-Id: Id54f45375b0051e57f9c9d59499c7c4c9d247500
4 files changed