Backport r18516: Ensure call numbers are returned to the holdings editor in ascending...

Backport r18516: Ensure call numbers are returned to the holdings editor in ascending sorted order

James Fournie in https://bugs.launchpad.net/evergreen/+bug/635121 reported
that call numbers were being displayed in the order that they had been
added to the database, rather than in sorted call number label order.

Although I have been unable to reproduce this problem on two different
test systems, the patch he provided for 1.6.1 (which fixes the problem on their
test system) shouldn't hurt other systems.

git-svn-id: svn://svn.open-ils.org/ILS/branches/rel_1_6@18521 dcc99617-32d9-48b4-a31d-7c20da2025e4