Removed: usage of Exception to detect if setup wizard is to be launched

An InvalidArgumentException might be used inside the loader, this is not
an efficient way to know whether the setup wizard is to be launched or
not.

In case of config file corruption, the setup wizard might also be shown
since an InvalidArgumentException could be raised.
Merge pull request #54 from patrickallaert/RemoveExceptionForSetupDetection

Removed: usage of Exception to detect if setup wizard is to be launched