drop initialization flag on removed node

If the node is reattached later we want to rerun the initialization
logic to rebuild the controller.

Closes #135.

inject.js

@@ -225,6 +225,7 @@ chrome.extension.sendMessage({}, function(response) {
               let id = node.dataset['vscid'];
               let ctrl = document.querySelector(`div[data-vscid="${id}"]`)
               if (ctrl) {
+                node.classList.remove('vsc-initialized');
                 ctrl.remove();
               }
             }