Bug 13832 - Missing table header IDs on record holdings table in OPAC

Bug 13832 - Missing table header IDs on record holdings table in OPAC

All but two of the table headers in the item holdings table in the opac have identifiers. The remaining two should be added so they can be modified easily with CSS.

Test Plan:
1) Apply this patch
2) View the holdings table for a record
3) Note the new id field for the item holds column
4) Note the new id field for the hold prioirty column ( if enabled )

Followed test plan. Patch behaves as expected.
Signed-off-by: Marc Véron <veron@veron.ch>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>