No need to special-case xmlns and xml:lang
No need to special-case xmlns and xml:lang

lm_message_node_set_attribute already special-cases xmlns and xml:lang for us,
so code calling it shouldn't have to do that

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