PHP Fatal error:  Access level to Esensi\Model\Model::makeValidator() must be public 

Using Laravel 4.2, I get this error while running the unit tests and while using the model in my application:
```
PHP Fatal error:  Access level to Esensi\Model\Model::makeValidator() must be public (as in class Watson\Validating\ValidatingInterface) in C:\...\vendor\esensi\model\src\Model.php on line 188
```