Bug 28704: Library MARCOrgCode field needs maxlength attribute

Bug 28704: Library MARCOrgCode field needs maxlength attribute

This patch adds a maxlength attribute to the "MARC organization code"
field in the form for adding and editing libraries. The maxlength, 16,
matches the limit of the table column.

To reproduce the problem, go to Administration -> Libraries.
 - Add or edit a library
 - Fill the "MARC organization code" field with a string longer than 16
   characters, e.g. Decriminalization
 - When you save the record you will see an error.

Apply the patch and add or edit a library.
 - Confirm that you cannot enter more than 16 characters in the "MARC
   organization code" field.

Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>