LP#1699838 Scale back settings for staff-based hold placement

LP#1699838 Scale back settings for staff-based hold placement

For now, we will add just one new setting to optionally restore the old
behavior.  In the absence of a 'preferred pickup location', the staff
form will default to the staff workstation OU.

Also, add setting to seed data.

Signed-off-by: Dan Wells <dbw2@calvin.edu>
Signed-off-by: Kathy Lussier <klussier@masslnc.org>
Conflicts:
	Open-ILS/src/sql/Pg/950.data.seed-values.sql