Implements a single page app that uses Flask, Ajax, and Bokeh. The
implementation follows David Hamann's blog post here:
https://davidhamann.de/2018/02/11/integrate-bokeh-plots-in-flask-ajax/.
$ python3 -m venv flask-ajax-bokeh-env
$ source flask-ajax-bokeh-env/bin/activate
The first time the environment is activated install Flask and bokeh:
$ pip install Flask bokeh