bug 2000 - fix order of issuingrule lookup

bug 2000 - fix order of issuingrule lookup

Extended help on the alternate circulation rules
form to list the order of issuingrules lookup as
follows:

same library, same patron type, same item type</li>
same library, same patron type, default item type</li>
same library, default patron type, same item type</li>
same library, default patron type, default item type</li>
default library, same patron type, same item type</li>
default library, same patron type, default item type</li>
default library, default patron type, same item type</li>
default library, default patron type, default item type</li>

This includes modifying two routines in C4::Circulation to
follow this order: GetLoanLength() and GetIssuingRule().

The reason for this change is to have Koha exhaust all issuingrules
possibilities for a branch before checking the rules for
the default branch - this is consistent with what an admin
might expect from looking at the issuingrules forms, which display
settings a branch at a time, and is more consistent with how
circulation rules should work for indepdendent branches.

Signed-off-by: Joshua Ferraro <jmf@liblime.com>