Bug 18403: Guarantors

Bug 18403: Guarantors

Technically a kid from your library group could have a guarantor
attached to another
group of library, let's deal with this case.

Test plan:
- Create a kid from your library group
- With a superlibrarian staff user create a guarantor that is outside of
the group of
libraries of the kid
- Login with a limited staff user and confirm that on the patron detail
page you do not
see the link to the guarantor detail page.

Note that you see the firstname and surname of the guarantor
Q. should it be hidden?

Signed-off-by: Signed-off-by: Jon McGowan <jon.mcgowan@ptfs-europe.com>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>