Bug 7401 - Shelving Location facet

Bug 7401 - Shelving Location facet

This patch enables the shelving location facet as an
alternative to the branches fact in two situations:
A) SingleBranchMode is enabled
B) There is only one branch in the branches table

Test Plan:
1) Catalog multiple items with different shelving locations.
2) Test enable by enabling SingleBranchMode
3) Test enable by deleting all but one branch

Based on initial patch by Ian Walls.

Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Tested cases 2) and 3) successfully in OPAC and staff client

Signed-off-by: Paul Poulain <paul.poulain@biblibre.com>