Bug 15690: CardnumberLength should not be bigger than 16

Bug 15690: CardnumberLength should not be bigger than 16

borrowers.cardnumber is a varchar(16), so CardnumberLength should not
have a max > 16

Test plan:
Test different value in CardnumberLength ("20", "20,30", "40,")
Edit a patron a make sure the text display under the cardnumber input is
correct

Signed-off-by: Mark Tompsett <mtompset@hotmail.com>
Signed-off-by: Marc <veron@veron.ch>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>