chore(server.js): Add CSP support

The support is disabled by default, uncomment relevant lines to enable
it.

Author: IgorMinar

lib/nodeserver/server.js

@@ -190,6 +190,9 @@ StaticServlet.prototype.sendFile_ = function(req, res, path) {
   var self = this;
   var file = fs.createReadStream(path);
   res.writeHead(200, {
+    // CSP headers, uncomment to enable CSP
+    //"X-WebKit-CSP": "default-src 'self';",
+    //"X-Content-Security-Policy": "default-src 'self'",
     'Content-Type': StaticServlet.
       MimeMap[path.split('.').pop()] || 'text/plain'
   });