fixes #827: stubs out id_namespace to help batch association test pass
fixes #827: stubs out id_namespace to help batch association test pass

ndlib/scholarsphere,ndlib/scholarsphere,jeremyf/sufia,samvera/hyrax,samvera/hyrax,zhang4952/scholarsphere,samvera/hyrax,zhang4952/scholarsphere,zhang4952/scholarsphere,ndlib/scholarsphere,zhang4952/scholarsphere,jeremyf/sufia,samvera/hyrax