Bug 10217 - Make sure direct links to detail views work when there is no session

Bug 10217 - Make sure direct links to detail views work when there is no session

To reproduce:
- Make sure you do not have a session for the OPAC you will be testing
  with. Delete the CGISESSID session cookie if you have one.
- Go directly to a detail view, e.g.:
  /cgi-bin/koha/opac-detail.pl?biblionumber=1
- Observe the error "Can't use an undefined value as a HASH
  reference at /home/magnus/scripts/kohadev/opac/opac-detail.pl line 445."

To test:
- Apply the patch
- Reload the page with the error
- You should now see the detail view of the record, as usual

Thanks to Chris Cormack who suggested the fix for this!

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Tested according to test plan, confirmed patch fixes the problem.
All tests and QA script pass.
Signed-off-by: Jared Camins-Esakov <jcamins@cpbibliography.com>