Investigate using circle ci

[holdenk]

@rgbkrk found another project testing Spark integrations with circle ci which might be a good starting point. See https://github.com/tribbloid/spookystuff/blob/master/.circleci/config.yml

[rgbkrk]

One other cool thing about circle CI is that you can attach more than one image for other services: https://circleci.com/docs/2.0/executor-types/#using-multiple-docker-images

[holdenk]

That would be really great for testing that we work with Spark+K8 after K8 is merged in Spark 2.3 (although the K8 stuff has it's own solution to req parsing so we'd need some code changes too).

[holdenk]

Awesome @willingc got this of the ground. I'll create a follow up.