Bug 26233: (bug 25553 follow-up) Make date columns sortable on the edit items table

We were missing to pass the title-string to datatables.

Test plan:
Retest bug 26233, with appropriate dates

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>

Signed-off-by: Nick Clemens <nick@bywatersolutions.com>

Signed-off-by: Lucas Gass <lucas@bywatersolutions.com>

koha-tmpl/intranet-tmpl/prog/js/cataloging_additem.js

@@ -47,6 +47,7 @@ $(document).ready(function(){
     var itemst = KohaTable("itemst", {
         "aoColumnDefs": [
             { "aTargets": [ 0 ], "bSortable": false, "bSearchable": false },
+            { "aTargets": [ "title-string" ], "sType": "title-string" },
         ],
         'bPaginate': false,
         'bInfo': false,