Bug 13255: On-site checkout due date wrong if SpecifyDueDate is disabled

Bug 13255: On-site checkout due date wrong if SpecifyDueDate is disabled

If you have the SpecifyDueDate preference disabled and check something
out as an on-site checkout the due date seems to follow the default
circulation rule rather than restricted the checkout to that day.

Test plan:
0/ Disable SpecifyDueDate and enable OnSiteCheckouts
1/ Check an item out to a patron and check the 'On-site checkout'
checkbox
2/ Verify (screen and DB) that the due date is correct (today 23:59)

Signed-off-by: Mirko Tietgen <mirko@abunchofthings.net>
Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Works as described, passes tests and QA script.

Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>