Set up a demo instance

[jllorencetti]

A few projects have a button to deploy to Heroku, OpenShift, etc.
I think it's a nice way for people to take a look at a running instance.
But I need to check the docs to see how much changes would be necessary in the project.

Also I think it'd be easy to have a running demo in @pythonanywhere, I could probably create a scheduled task to recreate everything in a daily basis with an updated version of the next branch.

Example repos:
@quokkaproject's Quokka
@heroku's Template

Docs:
Heroku