Bug 19103: Fix Stored XSS in patron-attr-types.pl

Bug 19103: Fix Stored XSS in patron-attr-types.pl

To Test
1. Hit the page /cgi-bin/koha/admin/patron-attr-types.pl
2. Click on new patron attribute type
2. Add a text in the field Description that contain js.
2. Save the page.
3. Notice js is execute
4. Apply patch and reload, the js is escaped

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>