Author: Adam Piotrowski (adam@wellcommerce.org)
 /**
  * Warms up the cache.
  *
  * @param string $cacheDir The cache directory
  */
 public function warmUp($cacheDir)
 {
     $bundlesClasses = $this->loader->getManagedBundleClasses();
     if (count($bundlesClasses)) {
         $this->writeCacheFile($cacheDir . '/bundles.php', sprintf('<?php return %s;', var_export($bundlesClasses, true)));
     }
 }