JS routing. Fixes #12

Very rudimentary JS routing using a switch statement against `window.location.pathname`. This fixes the js error being thrown on all pages other than the homepage as reported in issue #12 
For the record, I think the cleanest way would be to detect whether the thing you want to enhance is present and if so, enhance it. That way, you don't have an invisible coupling of a URL with some components you "know" exists at that URL. Could just run the querySelector and see if the container is present. (In the Future, it'd just be a web component and its mere presence would trigger its enhancement). But the URL trick is fine for now imho.