Make copy status visibility match default config.copy_status settings

Make copy status visibility match default config.copy_status settings

Previous version of this patch had hardcoded copy status settings to
0, 7, 12 to match the "Available" settings, rather than the OPAC
visibility settings available from config.copy_status for each status.

Until config.copy_status.opac_visible translates into an opac_visible
attribute on the status element in the holdings XML, this is probably
the best we can do.

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