LP1874897 Staff catalog honors classification scheme

LP1874897 Staff catalog honors classification scheme

Use the org unit setting "cat.default_classification_scheme" to
determine which scheme to use when extracting the bib-level call number
for display in the Angular staff catalog.

This also modifies the API to look the value up so future calls to the
API will Just Work (and it's one less bit of data the browser has to
retrieve).

Signed-off-by: Bill Erickson <berickxx@gmail.com>
Signed-off-by: Jane Sandberg <sandbej@linnbenton.edu>
Signed-off-by: Galen Charlton <gmc@equinoxinitiative.org>