Bug 17976: Update test to include fines

Bug 17976: Update test to include fines

This patch updates the existing test to include checking the alternative
to items.fine syntax.

We could use the account_lines relation, however that would include
other charges linked to the checkout, for example rental charges.

I opt to add a new accessor to give us more options and refine to just
overdue fines.

Signed-off-by: Emily Lamancusa <emily.lamancusa@montgomerycountymd.gov>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>