Bug 15586 - References to Koha::Branches remain in unit tests

Bug 15586 - References to Koha::Branches remain in unit tests

The unit tests BiblioObject.t and Hold.t still have references to
Koha::Branches that need to be changed to Koha::Libraries. These tests
currently fail because of this.

Test Plan:
1) prove t/db_dependent/BiblioObject.t should fail
2) prove t/db_dependent/Hold.t should fail
3) Apply this patch
1) prove t/db_dependent/BiblioObject.t should pass
2) prove t/db_dependent/Hold.t should pass

Signed-off-by: Chris Cormack <chrisc@catalyst.net.nz>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>