Documentation for how to run Jupyter without a local install

It would be good to have backup plans if people can't get Jupyter notebook installed - running Jupyter without a local install. 

Given the existence of things like JupyterHub now, there should be plenty of options. We should decide on a strategy and add them to the Setup page for the workshop (https://reproducible-science-curriculum.github.io/rr-jupyter-workshop/setup/) 