Create a dev/staging environment

[victortrac]

There's only a single environment for discovery.etcd.io, which means that there's not an environment to test upgrades to GKE, etcd, or the discovery service itself. Once #8 is done, we should use that template to generate a pre-prod environment to enable testing of changes to the service.

[eduartua]

Two environment were created, dev and prod. Cloudkite terraform modules were used, see. The actual implementation here.