GetHardDueDate works just like GetIssuingRule, but it not only tests for having
found an row of results before returning, but checks for the existence of a
hard due date as well. That means that even if it finds a matching rule, unless
that rule has a hardduedate set it will toss it and keep looking!

So, for example, even though there is a matching rule for say "STAFF / VIDEO / *", but it has no hardduedate. So it gets tossed and the subroutine keeps looking. If the next match, "STAFF / * / *" *has* a hardduedate, it is the one returned.

This means that if a more specific rule has no hard due date, it is overridden by a less specific rule that does have a hard due date.

TEST PLAN:
1) Create 2 issuing rules, one more specific with no hard due date, one less specific *with* a hard due date. See my description above for an example.
2) Issue an item to a borrower where the more specific rule should apply, and the checkout should not receive a hard due it.
3) Observe that it *does* receive a hard due date.
4) Apply the patch, and repeat step 2.
5) Observe that the checkout *does not* receive a hard due date.