Bug 14418: XSS flaw in opac-shelves.pl

Bug 14418: XSS flaw in opac-shelves.pl

To test:
1/ Create a list and add at least one item to it
2/ Hit a url like http://192.168.2.18/cgi-bin/koha/opac-shelves.pl?viewshelf=7&sort=author&direction=%22%3E%3Cscript%3Ealert%28%27oh%20noes%27%29%3C/script%3E
  Where the shelf id is the number of the list you created, notice the js is executed
3/ Apply the patch
4/ Reload the page notice the js is now escaped

Signed-off-by: Jonathan Druart <jonathan.druart@koha-community.org>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@unc.edu.ar>