add nonblocking js fragment

Author: jontsai

_includes/themes/htk/default.html

@@ -24,5 +24,6 @@
     {% include themes/htk/fragments/header.html %}
     {% include themes/htk/fragments/main.html %}
     {% include themes/htk/fragments/footer.html %}
+    {% include themes/htk/fragments/js/nonblocking.html %}
   </body>
 </html>

_includes/themes/htk/fragments/js/nonblocking.html

@@ -0,0 +1,6 @@
+<script>
+  ((window.gitter = {}).chat = {}).options = {
+    room: 'hacktoolkit/hacktoolkit'
+  };
+</script>
+<script src="https://sidecar.gitter.im/dist/sidecar.v1.js" async defer></script>