LP1966995: Bootstrap Opac: fix display of 856 $n, $z, and $3

LP1966995: Bootstrap Opac: fix display of 856 $n, $z, and $3

This fixes the display in the Bootstrap Opac for the 856 subfields n, z, and
3.

To test:

1. Create a record(s) with 856 fields which contain a combination of
subfield n, z and 3's.
2. Prior to the patch the fields do not display in the bootstrap opac.
3. Apply the patch.
4. The fields will now display.

Signed-off-by: Garry Collum <gcollum@gmail.com>
Signed-off-by: Carol Witt <wittc@cwmars.org>
Signed-off-by: Galen Charlton <gmc@equinoxOLI.org>