Think about deploying directly with docker

[steven-murray]

At the moment, we rebuild the docker image on the server whenever we make updates, which requires having the repo on the server. Perhaps this is the best way to do things, but it might be nice to be able to auto-deploy the docker image from Github, and pull it onto the server with a webhook, and just run the new docker container (without ever downloading the repo).

A mid-way alternative would be to listen to some webhook on merge to master on GitHub (from the server), and just do a git pull and remake the docker instance there.