Fixed possible notice with driver "files"
Fixed possible notice with driver "files"

PHPSocialNetwork/phpfastcache,PHPSocialNetwork/phpfastcache,Geolim4/phpfastcache,Geolim4/phpfastcache,bukowskiadam/phpfastcache,bukowskiadam/phpfastcache,bukowskiadam/phpfastcache