Do not Autoload when checking for inverse class_exists. Fails with autol...

Do not Autoload when checking for inverse class_exists. Fails with autoload in some cases. According to the php documentation: http://php.net/manual/en/function.class-exists.php

bool class_exists ( string $class_name [, bool $autoload = true ] )

We do not want to autoload this class, we want the autoloader from symphony to do that for us. This causes some strange problems when used in combination with other libraries.