This addresses #58.

Changes:

• archive -> archives as the latest version of goreleaser only recognize the plural one
• add tvm to the goreleaser builds (also add build id otherwise it defaults to project_name)
• add note to readme to say that tvm is included

Tested it by pushing tag and running

docker run --rm --privileged -v $PWD:/go/src/github.com/uber/astro -v /var/run/docker.sock:/var/run/docker.sock -w /go/src/github.com/uber/astro -e GITHUB_TOKEN=<> goreleaser/goreleaser  release --rm-dist

I've seen that goreleaser was successful and the tarballs with both astro and tvm were published to github.