Update Dockerfile and add docker-compose
This should streamline the Docker initialization process since we can now use the skinny Alpine linux base image for Ruby 2.4.4 and we really shouldn't need to bend over backwards to install Node.js since all we rely on it for is Yarn which has its own Alpine (apk) package.
Also extracted the boot stuff into a Procfile that foreman (or Docker) can consume.
Now we have to figure out the Google OAuth issue when first loading the app up.

Hmm that's weird. Granted, I've yet to get my non-docker local setup to work with Google. I probably have the credentials setup wrong. Happy to help once I get it sorted out!
@olivierlacan I just got my credentials working and google oauth is working as expected within docker. Might be a ENV config issue?
@joeltaylor Oh no, I meant pre-configuration we shouldn't try to ping Google with fake creds. Its the .env defaults that shouldn't exist.
@joeltaylor Did a bunch of updates since you last reviewed this. Including some initial setup for Sidekiq and Redis containers. Let me know what you think.