python text using an internal git repo

This is a sample jupyterhub setup for a jupyterbook. Basic approach:

1. bind mount two directories -- a github repository for the notebooks (read-only) and a home_dirs repository for persisting user notebooks spawned by docker spawner.

2. To try this out on localhost:

   cp -a notebooks_source git_repo
   cd git_repo
   git init
   git add -f *
   git commit -m 'init'
   

   Then:

   a) docker-compose build content
   b) docker-compose build jupyterhub
   c) docker-compose build notebook d) docker-compose up

   server should be running on localhost:8500 with dummyAuthenticator

next steps

Add apache webserver to serve _build/html/ files that pull individual notebooks from a github repo