Remove `autoload :Specification`
Remove `autoload :Specification`

- This class was removed in 2010 but the autoload was neglected 64b8b5
- Closes #4050

bronzdoc/bundler,davydovanton/bundler,bundler/bundler,asutoshpalai/bundler,Teino1978-Corp/Teino1978-Corp-bundler,mvz/bundler,jingweno/bundler,Teino1978-Corp/Teino1978-Corp-bundler,pivotal-cf-experimental/bundler,bronzdoc/bundler,bundler/bundler,pivotal-cf-experimental/bundler,seanlinsley/bundler,mpapis/bundler,RochesterinNYC/bundler,mvz/bundler,mpapis/bundler,davydovanton/bundler,seanlinsley/bundler,jingweno/bundler,RochesterinNYC/bundler,asutoshpalai/bundler,dilumnavanjana/bundler,dilumnavanjana/bundler