Bug 19086: (follow-up) Fix Stored XSS in supplier.pl

Bug 19086: (follow-up) Fix Stored XSS in supplier.pl

In preparation:
Make sure you enter <script>alert("sth")</script>
in all fields of a new vendor that are not validated
and save.

1) Access vendor summary page.
2) Verify scripts are executed
3) Apply patch
4) Verify scripts are on longer executed

This works in combination with the other patches for XSS
on this bug.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>