Bug 14816: Fix multiple selection in item search

Bug 14816: Fix multiple selection in item search

Send each selected value as a separate parameter. Otherwise DataTables
(or jQuery ?) joins all values with a comma

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
I could not reproduce the bug when selecting multiple home libraries,
but I could by selecting multiple item types or collection codes. The
patch allowed those queries to complete correctly.

Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Brendan Gallagher <bredan@bywatersolutions.com>