Connects to #130. Continuous delivery pipeline using Cloud Build.

[jimmyzhen]

Technical notes

1. No code changes except for the newly added *.yaml and *.conf files required to set up the pipeline.
2. To-do items upon merging this PR:
   • Map DNS to cluster (for dev and staging instances)
   • Enable SSL cert for the cluster
   • Enable authenticated access to IAM users (for dev and staging instances)

Steps to test:

1. Expose the deployed cluster to be accessible externally.
2. Visit the cluster's external IP in the browser and expect to be able load the site.