Bug 13036 - Exclude control columns from sorting on staff client catalog detail page

Bug 13036 - Exclude control columns from sorting on staff client catalog detail page

The checkbox and "edit" column in the table of holdings on the
staff client detail page should be excluded from sorting since there is
no useful data to sort. This patch does so.

To test, view the detail page for a title which has multiple items.
Confirm that sorting works correctly.

Test under the following conditions:

 - with the StaffDetailItemSelection system preference enabled and
   disabled.
 - as users who do and do not have cataloging item edit privileges

Signed-off-by: Chris Cormack <chris@bigballofwax.co.nz>
Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
Works as desrcibed, no problems found.

Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>