adding golang-builder Dockerfile
adding golang-builder Dockerfile

Signed-off-by: Bohan Chen <c9a015a7f6482b47c219aa2cbd78ba6c88c0a327@pivotal.io>
Co-authored-by: Bishoy Youssef <9b4d1ba1708a9b42aa1e22343aa1f23ecf97ab43@pivotal.io>

concourse/concourse,concourse/concourse,concourse/concourse,concourse/concourse,concourse/concourse