Fix to shrink image size https://docs.docker.com/articles/dockerfile_best-practices/
Fix to shrink image size
https://docs.docker.com/articles/dockerfile_best-practices/

kou/msgpack-ruby,larskanis/msgpack-ruby,cosmo0920/msgpack-ruby,cosmo0920/msgpack-ruby,ojundt/msgpack-ruby,larskanis/msgpack-ruby,okkez/msgpack-ruby,msgpack/msgpack-ruby,msgpack/msgpack-ruby,cosmo0920/msgpack-ruby,okkez/msgpack-ruby,msgpack/msgpack-ruby,kou/msgpack-ruby,ojundt/msgpack-ruby,ojundt/msgpack-ruby,larskanis/msgpack-ruby,ojundt/msgpack-ruby,kou/msgpack-ruby,cosmo0920/msgpack-ruby,okkez/msgpack-ruby,kou/msgpack-ruby,okkez/msgpack-ruby,larskanis/msgpack-ruby