Improved the nginx config

Signed-off-by: Janos SUTO <sj@acts.hu>

contrib/webserver/piler-nginx.conf

@@ -4,7 +4,13 @@ server {
 
         root /var/piler/www;
 
-        gzip  on;
+        server_tokens off;
+
+        add_header X-XSS-Protection "1; mode=block";
+        add_header X-Content-Type-Options "nosniff";
+        add_header Referrer-Policy "same-origin";
+
+        gzip on;
         gzip_types text/plain application/xml text/css;
         gzip_vary on;