Dev environment web server should return index.html for any request

[ReidWilliams]

It's unproductive to develop single page apps where a request to a route means the server should return index.html and the page should render based on the route.

[ReidWilliams]

This has been fixed here:
https://github.com/ReidWilliams/hello-react/tree/e768f4fb4c77106acc43e41a2707720637c60d39

Needs to be replicated here.