Bug 7703: (QA follow-up)

Bug 7703: (QA follow-up)

Revised test plan from Owen:

This patch modifies the hold process so that if one of the titles in a
multi-hold process has no items the process doesn't abort completely.

To test, apply the patch and perform a search in the catalog which will
return one or more records with no items attached.

 - Check checkboxes for multiple results, some of which have items and
   at least one of which has no items.
 - Click "Place hold."
 - You should be taken to the page for placing multiple holds, with a
   heading, "Cannot place hold on some items."
 - Note: You will not be able to complete the holds process without the
   next patch.

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Signed-off-by: Sally <sally.healey@cheshiresharedservices.gov.uk>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>