Only generate Contact header from transport if Request URI contains a hostname on incoming INVITE

darcs-hash:20090304122228-58103-a04b97272a32d6ae0b617b610f7a630e4b52d7be
Update transport parameter on Request URI from Route object on outgoing INVITE

darcs-hash:20090304124419-58103-654d8b66a04978acfa3f58c96c8ba51e8b6579a8