Bug 19086 Stored XSS in subscription-add.pl

Bug 19086 Stored XSS in subscription-add.pl

To Test
1. Hit the page /cgi-bin/koha/serials/subscription-add.pl
2. Add a text in the field Public note and Nonpublic note
   that contains js (Internalnotes, notes)
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>
(cherry picked from commit ebf781afc133508eddcb8dc8fb6d7429a72db99b)
Signed-off-by: Fridolin Somers <fridolin.somers@biblibre.com>
(cherry picked from commit c4a1eafb5bac265c936567807e94ab22d04a1094)
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>