Rewrite the app using jQuery and Backbone.js

You can try it out before we decide to merge and deploy this:

check out this branch then hit:
`http://localhost:8000/` -- default explanation page.
`http://localhost:8000/#mozilla/969521` -- bug page
"Old-style" `http://localhost:8000/?id=969521` will continue to work (though the URL will end up looking like `http://localhost:8000/index.html#mozilla/969521` in order to make it work with Backbone.js)

In the future we can define routes for `/#chrome/`, `/#ie/`, etc. 

And if we decide we want to put up a backend component to this--we can ditch the hash URLs (ohai @karlcow).

This fixes a handful of issues. Hopefully it creates less. :8ball: