Nix package

I haven't really tried Nix yet myself, but after reading this discussion I wondered if it would be useful here: https://discourse.nixos.org/t/is-there-much-difference-between-using-nix-shell-and-docker-for-local-development/807

It sounds like it could eliminate a lot of bug reports you get from people saying it doesn't work on their machine. Better than docker, or docker alone.