Bug 27430: Use password minimum length for patron category on password hint

Bug 27430: Use password minimum length for patron category on password hint

Hint for password minimum length should use minimum length
set for patron category  not "minPasswordLength" value.

To test:
1. Set "minPasswordLength" e.g. 6
2. Set "Patron" category minimum password length e.g. 4
3. Create new a patron.
4. Note that hint after password input field reads "Minimum
   password length: 6"
5. Apply patch.
6. Hint should now read "Minimum password length: 4".

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Sally <sally.healey@cheshiresharedservices.gov.uk>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>