Feature/docker

[wayland]

Hi!

I found that:

• There was no setup for Docker, which is something that a lot of people would be looking for
• I wasn't interested in installing Nix when their recommended installation method said "Turn off selinux"

So, I made a docker setup that will allow people to run:

• make docker-build-test -- this runs the tests in a docker container
• make docker-build -- this builds a docker image for use containing PostgREST-OpenAPI

Hopefully not needing Nix (though it's still there) will enable more people to get into the development.

Thanks!

Edit: Also added a make docker build-and-run which should produce a running version with postgrest attached; useful for development