Set due times for durations measured in days to 23:59:59 after inserts OR updates

Set due times for durations measured in days to 23:59:59 after inserts OR updates

The existing trigger acted only on the initial insert of a circulation
transaction for duration intervals perfectly divisible by 24 hours.
If updates to those due dates were subsequently issued, then the due
time would revert to 00:00:00 - which could cause surprising overdue
fines to be generated on the due date, rather than after the due date.

This commit makes the trigger take effect on both INSERT and UPDATE
to the action.circulation table.

git-svn-id: svn://svn.open-ils.org/ILS/branches/rel_1_6@18129 dcc99617-32d9-48b4-a31d-7c20da2025e4