Friendly 404 page?

[ataylor32]

Currently, 404 errors are handled like this:

res.status(404).send('404 | Page Not Found')

Since this is a demo app, it would be nice to see a demo of handling 404 errors properly. To me, that means keeping the "shell" of the Vue app (still reactive and everything) with a message like "The page you requested was not found. Please follow one of the links above."

EDIT: It should also still have the "404" status code.