LP#1538691: More changes to terminology

LP#1538691: More changes to terminology

For more consistency: Changing all staff client instances of Copy Location to
Shelving Location. We also replace Volume with Call Number and use Holdings
for a combination of copies/volumes. Also replacing the 'Add Copies' option
on the bib record page with 'Add Holdings' as was previously discussed on
the open-ils-general list.

Signed-off-by: Kathy Lussier <klussier@masslnc.org>
Signed-off-by: Dan Wells <dbw2@calvin.edu>