Add dockerfile

[ycjungSubhuman]

This dockerfile is associated with issue #2.

Usage:

cd docker/
docker build -t diff3f . # this takes some time due to the compilation of xformers
docker run -it --name diff3f --gpus all -v $PWD:/workspace -p 8888:8888 diff3f /bin/bash
cd workspace/
jupyter-lab --allow-root --ip "0.0.0.0"

The build with Dockerfile may not be reproducible in a far future. Distribution as an docker image, e.g., via docker hub, is suggested.