Bug 13470 - pay fines with extended borrower attributes result in application error

Bug 13470 - pay fines with extended borrower attributes result in application error

Test scenario:

1. ensure that extended patron attributes are turned on in system preferences
2. find borrower which has fine to pay, and click on pay button
3. verify application error
4. apply patch and verify that application error is gone

Signed-off-by: Aleisha <aleishaamohia@hotmail.com>
Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>