Dockerfile: split into two stages
Dockerfile: split into two stages

build with --target base to quickly build and push an image to test in a
live cluster

Signed-off-by: Alex Suraci <925ba519bbf1a06224928b692ef88b93aee946af@gmail.com>

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