Move headroom to bundle

src/bundle.js

@@ -146,3 +146,9 @@ var screenfull = require("screenfull");
 _define("screenfull", function () {
     return screenfull;
 });
+
+// headroom.js
+var headroom = require("headroom.js/dist/headroom");
+_define("headroom", function () {
+    return headroom;
+});