Flask app to embed a bokeh server app

Simple example to reproduce bokeh/bokeh#4693

Use conda to create the environment:

$ conda env create

In one terminal, run bokeh server:

$ source activate flask_bokeh_app
$ bokeh serve --host localhost:5000 --host localhost:5006 sliders.py

In another window, run flask:

$ source activate flask_bokeh_app
$ export FLASK_APP=app.py
$ flask run

Go to http://localhost:5000/