Example configuration leads to issue

Hi,

thank you for your work on this module!

I installed it on my test machine and encountered an issue when I used the example configuration provided on the project page. I had to add the line

$conf['cache_backends'][] = 'sites/all/modules/contrib/cache_heuristic/memcache.deferred.inc';

in between the lines

// Use mem cache as default backend for cache heuristic (requires the memcache module)
$conf['cache_backends'][] = 'sites/all/modules/contrib/memcache/memcache.inc';
$conf['heuristic_cache_default_class'] = 'MemCacheDrupalDeferred';

or else page requests failed with this error message given:

Fatal error: Class 'MemCacheDrupalDeferred' not found in /var/www/web01prod/sites/all/modules/contrib/cache_heuristic/cache_heuristic.inc on line 148