Dockerizing the project.

I've created a simple Dockerfile to be able to run this node app using a Docker container.

Cheers,

`Repo` can be any valid identifier and same goes for `tag` (usually, a version number is provided). However, the choice of name is still undecided (for the maintainers to decide). If you'd like to create an automated build on Docker hub, we can decide on the names then.