Default number of ACQ copies per provider

Default number of ACQ copies per provider

Acquisitions providers have a new "Default # Copies" field.  When the value
is set, this number of copies will be automatically added to each lineitem
added to a purchase order for the provider.  This takes place during PO
creation from a selection list or existing bib record and when a lineitem is
added to an existing purchase order.  If a lineitem already has copies
attached, no default copies are added.

Signed-off-by: Bill Erickson <berick@esilibrary.com>