Added support for Docker

[stefins]

What this PR contains?

Added support for Docker to work in container based environments

[aljazerzen]

I believe adds the two files to build a docker image. There should also be instructions how to do this added to the README.

In a nutshell, to build the image, you have to run:

docker build . -t mulco

This will build the image that can then be run with:

docker run --rm -p 5000:5000 -v $(pwd):/moul moul preview

$(pwd) can be replace with absolute path to your moul collection.

As far as I know this PR seem ok to merge.