connectorClass option is not working

[Seb33300]

Hello,

I am trying to override the Connector service using the connectorClass option.

But it looks like this option doesn't work as expected since the original connector class CKSource\CKFinder\CKFinder is always loaded.

This is because the class name is hardcoded in the factory:
https://github.com/ckfinder/ckfinder-symfony-bundle/blob/master/Factory/ConnectorFactory.php#L49

Here is the PR to fix the issue:
#22