Add attributes to in-db unapi acp, sunit, holdings_xml

Add attributes to in-db unapi acp, sunit, holdings_xml

This gives us more flexibility in displaying due dates within search
results or other contexts in which holdings are displayed. The
age_protect, copy_id, and vol_id attributes are required by the record
summary display.

While we're at it, fix the type conflicts in unapi.circ.  Due to the
change in positional arguments, $2 is now $9; thankfully PostgreSQL
complained about the difference in types.

Signed-off-by: Dan Scott <dscott@laurentian.ca>