Fix Nginx example config

Check https://stackoverflow.com/questions/15423500/nginx-showing-blank-php-pages#16887296
for the rest of the change (without, I get white page on a testing
vagrant box)

mods/sample-nginx.config

@@ -129,9 +129,8 @@ server {
     # With php5-fpm:
     fastcgi_pass unix:/var/run/php5-fpm.sock;
 
-    include fastcgi_params;
+    include fastcgi.conf;
     fastcgi_index index.php;
-    fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
   }
 
   # deny access to all dot files