Add Google analytics code to browser demo

demo/browser.html

@@ -35,5 +35,13 @@
   <div id="editor"></div>
   <iframe width="600" height="775"></iframe>
   <script src="bundle.js"></script>
+  <script>
+  (function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
+  (i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
+  m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
+  })(window,document,'script','//www.google-analytics.com/analytics.js','ga');
+  ga('create', 'UA-48340245-1', 'pdfkit.org');
+  ga('send', 'pageview');
+  </script>
 </body>
 </html>