Feature request: Option to rewrite paths to serve start-path

[rundis]

Firstly tx for a very handy npm lib.

Had a hard time coming up with a short description, so here's a bit of context:

• I have a single page app using elm-transit-router
• When navigating between pages it changes the browser-url according to how I set up routing

So a typical scenario in my sample app (https://github.com/rundis/albums):

• elm-server Main.elm --output main.js --start-path index.html
• I get an url like: http://localhost:3001
• I navigate to an artist listing page and get a browser-url: http://localhost:3001/artists
• I make a change in some elm file
• elm-server recompiles as expected, but my browser does a get request to http://localhost:3001/artists
  which I suppose is fair play, but unfortunately that obviously results in a 404.

That sort of ruins the flow quite a bit. So it would be super awesome if there was some solution to handle this scenario. Maybe a glob-pattern to tell the server to serve (say index.html) for any url in the glob pattern ?