fix the rb-media-store: backend store wasn't initialized
fix the rb-media-store: backend store wasn't initialized

git-svn-id: cfad8b3cc1744551a46e4cfa82812f6b42324c04@1277 8402a193-bf1e-0410-a7e5-8246bfde4f7d

cqcallaw/rhythmbox-upnp-coherence