Adds Dockerfile and README instructions

[lodi-g]

I couldn't build eos on my computer because of incompatibility between Python packages, I therefore decided to create a Dockerfile for it.

Now that it seems to work from my tests, I'm creating a PR so everyone can profit from it.

Building lxml takes a few minutes on my machine, maybe this should be mentioned in the Installation#Docker section?

[sylvaindeloux]

👍🏻