Create a scene

[kodikos]

This PR gets to the meat of the demonstration by setting up a (badly drawn!) a single scene with some narrative that you can step through. It includes the following:

• Updating the readme
• Removing bits of the react app we don't need and replacing it with the top level components for displaying the scene
• Setting up a responsive display for the app scenes
• Adding styled components that might get some reuse
• Adding a super-class for scenes to use that facilitates stepping through subscenes
• Adding the first scene markup