LP1821950 & LP1980409 Option to require call number label

LP1821950 & LP1980409 Option to require call number label

This uses a new Library Setting for "Require call number labels
in Copy Editor" for the benefit of libraries that with to use a
predefined Prefix (such as FIC or EZ) instead of individual call
number labels for each volume.

When the setting is True, the call number label field is marked
required and the Save buttons disabled until a value is present.

When the setting is False, the call number label is not required.
In addition, the Angular interface adds an additional check for
Prefix, so if the call number label is empty then the Prefix is
required.

Acknowledgements:
Org Unit Setting created by Kyle Huckins
Angular and AngularJS changes done by New Developers Working Group

Signed-off-by: Terran McCanna <tmccanna@georgialibraries.org>
Signed-off-by: Michele Morgan <mmorgan@noblenet.org>