private-tubes-factory: use gabble_tube_dbus_channel_allowed_properties instead of our own version of it
private-tubes-factory: use gabble_tube_dbus_channel_allowed_properties instead of our own version of it

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