Merge pull request #32 from rl-king/fixnotes

Fix notes, popstate is dispatched by window not document

notes/navigation-in-elements.md

@@ -19,7 +19,7 @@ var app = Elm.Main.init({
 });
 
 // Inform app of browser navigation (the BACK and FORWARD buttons)
-document.addEventListener('popstate', function () {
+window.addEventListener('popstate', function () {
     app.ports.onUrlChange.send(location.href);
 });