msgr: encode sockaddr.ss_family big endian in ceph_entity_addr

msgr: encode sockaddr.ss_family big endian in ceph_entity_addr

The ss_family field is normally host endianness, but we
want to exchange ceph_entity_addr across the wire and store
it on disk.  So, encode ss_family in big endian (to match
the other sockaddr field endianness).

Rev disk and wire protocols to match.