Bug 13917: OPAC: Putting holds still possible by URL even if turned off by system...

Bug 13917: OPAC: Putting holds still possible by URL even if turned off by system preference

To test:

1)
Prepare an URL that put's a hold in OPAC (see comment #1), e.g.
[YOUR SERVER]/cgi-bin/koha/opac-reserve.pl?biblionumbers=1

2)
Set system preference 'RequestOnOpac' to 'Don't allow patrons to place holds on items from the OPAC.'

3)
Go diectly to this URL.
Result: The page displays to confirm hold (wrong)

4)
Apply patch

5)
Repeat step 3
Result: Redirect to 404 page (OK)

6)
Set system preference to "Allow"

7)
Repeat step 3
Result: The page displays to confirm hold (OK), like it would be from link in OPAC.

Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>
(cherry picked from commit 20dc9ce5a1255fa7722e23b9300de19ec35eda16)
Signed-off-by: Chris Cormack <chris@bigballofwax.co.nz>