Create the narrowbar using a Handlebars template

This fixes an XSS hole (#249).

(imported from commit 5f70c0bc23e0d992f2d85889e2ba9157f1b73b3a)

zephyr/static/js/setup.js

@@ -13,7 +13,8 @@ $(function () {
     }
 
     // Compile Handlebars templates.
-    $.each(['message', 'subscription', 'userinfo_popover_title', 'userinfo_popover_content'],
+    $.each(['message', 'subscription', 'narrowbar',
+            'userinfo_popover_title', 'userinfo_popover_content'],
         function (index, name) {
             templates[name] = Handlebars.compile($('#template_'+name).html());
         }