nginx: Add snippet for custom server block config.

nginx/files/nginx/snippets/evolinux_server_custom

@@ -0,0 +1,7 @@
+# Evolinux custom configuration, to be used in all server blocks
+
+location ~ /\.(inc|git|bak|env) {
+  # We don't want to let the client know a file exist on the server,
+  # so we return 404 "Not found" instead of 403 "Forbidden".
+  return 404;
+}

nginx/templates/evolinux-default.conf.j2

@@ -49,6 +49,8 @@ server {
         stub_status on;
         access_log off;
     }
+
+    include /etc/nginx/snippets/evolinux_server_custom;
 }
 
 server {