Bug 22626: 'Filter paid transactions' broken on Transactions tab in staff

Bug 22626: 'Filter paid transactions' broken on Transactions tab in staff

This patch changes a parameter in the function which filters the
DataTable of transactions. The addition of more columns to the table
changed the index of the column which is being filtered.

To test, apply the patch and locate a patron who has multiple fines or
charges, some of them paid. Go to Accounting -> Transactions. Test the
"Filter paid transactions" link. Table rows which show "0.00" in the
"Oustanding" column should be hidden.

Signed-off-by: Liz Rea <wizzyrea@gmail.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>