SAK-22629 Support paging through jobscheduler API.

When there are a large number of triggers in the DB we were loading them all in the tool. This was very slow an consumed lots of memory. Now the paging is done by the DB.

git-svn-id: https://source.sakaiproject.org/svn/jobscheduler/trunk@120195 66ffb92e-73f9-0310-93c1-f5514f145a0a