Bug 18560: RSS link in opac shelves is broken

Bug 18560: RSS link in opac shelves is broken

TEST PLAN
---------
1) have books entered
2) log in create a list
3) add books to list
4) display list
5) click the RSS link button.
   -- bad HASH error.
6) apply patch
7) repeat steps 4&5
   -- readble junk without error messages.
8) run koha qa test tools

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Julian Maurice <julian.maurice@biblibre.com>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>
(cherry picked from commit f3167a5259a5adb5cc00455bb81a269e29081742)
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>