service: tasker: dont always run it, fire it via alarmmanager

we dont need this service to run all the time, rather its "fire and forget"

rewrite every call to the service and the service itself.
now we set an alarm, which fires the service.

this is way more memory and battery saving.

also fix the Shell, only debug if debug is set in Application.

Change-Id: I6c36cf9e2a72ce852380e5cbef9e18db10a9e15a