Turn GabbleServerSaslChannel's dispose into finalize
Turn GabbleServerSaslChannel's dispose into finalize

There's actually nothing left there that releases refs.

Ziemin/telepathy-gabble,mlundblad/telepathy-gabble,mlundblad/telepathy-gabble,jku/telepathy-gabble,mlundblad/telepathy-gabble,jku/telepathy-gabble,Ziemin/telepathy-gabble,Ziemin/telepathy-gabble,Ziemin/telepathy-gabble,jku/telepathy-gabble