mark this branch as dev version, make users not to install this
mark this branch as dev version, make users not to install this

cosmo0920/msgpack-ruby,ojundt/msgpack-ruby,ojundt/msgpack-ruby,msgpack/msgpack-ruby,msgpack/msgpack-ruby,cosmo0920/msgpack-ruby,cosmo0920/msgpack-ruby,ojundt/msgpack-ruby,cosmo0920/msgpack-ruby,msgpack/msgpack-ruby,ojundt/msgpack-ruby