Improve fastcgi configuration for PHP-FPM (increase buffers size)

roles/webserver/templates/fpm/nginx/fastcgi_pass_fpm.j2

@@ -3,3 +3,5 @@ fastcgi_split_path_info ^(.+\.php)(/.+)$;
 include fastcgi_params;
 fastcgi_pass fpm-backend;
 fastcgi_index index.php;
+fastcgi_buffer_size 8m;
+fastcgi_buffers 8 8m;