Made project use a callback provider to avoid letting almost the whole world on blank

nginx/00-callback-provider-cache.conf

@@ -0,0 +1,2 @@
+# Included inside nginx's http block by the stock nginx.conf.
+proxy_cache_path /var/cache/nginx/callback-provider levels=1:2 keys_zone=callback_provider:10m inactive=7d max_size=2g use_temp_path=off;