Fix binary autoload require

I installed the lib with composer in a project where the binary folder was `bin/`, and I got an error trying to run the binary.

```
PHP Warning:  require_once(/var/www/framework-standard-edition/vendor/classpreloader/classpreloader/vendor/autoload.php): failed to open stream: No such file or directory in /var/www/framework-standard-edition/vendor/classpreloader/classpreloader/classpreloader.php on line 4
PHP Fatal error:  require_once(): Failed opening required '/var/www/framework-standard-edition/vendor/classpreloader/classpreloader/vendor/autoload.php' (include_path='.:/usr/share/php:/usr/share/pear') in /var/www/framework-standard-edition/vendor/classpreloader/classpreloader/classpreloader.php on line 4
```