docker-image: clean up, ruby2.3, go1.9, gcloud 157, ginkgo
docker-image: clean up, ruby2.3, go1.9, gcloud 157, ginkgo

- change golang, ruby installations
- add test dependencies (ginkgo)

cloudfoundry-community/stackdriver-tools,cloudfoundry-community/stackdriver-tools,cloudfoundry-community/stackdriver-tools,cloudfoundry-community/stackdriver-tools