constants: add PROPERTY_FLAGS_RW for convenience
constants: add PROPERTY_FLAGS_RW for convenience

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