Add Dockerfile

[evroon]

A Dockerfile can be very useful as the dependencies are not that easy to install. It took me a few hours to figure out how to get it to work, so hopefully this could save others some time, even though the Dockerfile is quite simple in the end.

It can be build and run by using for example:

docker build -t liteflownet/pytorch:latest docker
docker run --gpus all -it liteflownet/pytorch:latest /bin/bash

[sniklaus]

Thank you for this contribution! I added a reference to this pull request in the readme such that anyone interested can find it. 👍