Docker DM Stack installation instructions (for home/travis-ci use)

[drphilmarshall]

Make tutorial or notes showing how to use docker to recreate the Stack Club environment at home, or at travis-ci.org. I am motivated to work on this by my own stack installation going stale through conda binary support being dropped, but feel free to self-assign if you'd like to help me with this task. Belongs to epic #15

[drphilmarshall]

I think the primary need for a Docker tutorial is for users looking to work with the Stack offline, away from the LSP, on their laptops etc - rather than on travis-ci, but of course if we can set up the LSP environment at home with a single dockerfile, then we can use the same dockerfile at travis. @heather999 , you were investigating this - let us know what you find out, and how you recommend we can take part in the Stack Club @ Home! :-)