LP1155769: Items repeated in tpac display, others not visible

This was an issue with the query and ordering by a column that was
sometimes null (copy_number).  Added barcode to be a sort rather than
replacing copy_number, per bshum's suggestion.  Not replacing allows
libraries that use copy_number to continue to use them as well.

Signed-off-by: Kyle Tomita <tomitakyle@gmail.com>
Signed-off-by: Ben Shum <bshum@biblio.org>