[2.0] Changing sandbox to use ArrayCache by default so it doesn't require APC....

[2.0] Changing sandbox to use ArrayCache by default so it doesn't require APC. Added comment with APC as the recommended for production

tools/sandbox/config.php

@@ -7,7 +7,8 @@ $classLoader->setBasePath('Doctrine', realpath(__DIR__ . '/../../lib'));
 $classLoader->setBasePath('Entities', __DIR__);
 
 $config = new \Doctrine\ORM\Configuration;
-$cache = new \Doctrine\Common\Cache\ApcCache;
+$cache = new \Doctrine\Common\Cache\ArrayCache;
+// $cache = new \Doctrine\Common\Cache\ApcCache; # RECOMMENDED FOR PRODUCTION
 $config->setMetadataCacheImpl($cache);
 $config->setQueryCacheImpl($cache);