Allow authoring build config in EDN instead of YAML
We're Clojurists! You're Clojurists! We'd love to be able to replace `.circleci/config.yml` with EDN. I guess we could check in an EDN file and generate YAML from it and check that in too, but the duplication is even less palatable.
This is probably too wild but in a wonderful future world, we could use Clojure 1.9's tools.deps and code-generate a config file at the start of each build.