Make CalibratedClassifier accept any arbitrary calibrator and classifier

[perellonieto]

The current calibratedClassifier was designed only for Beta calibration, sigmoid and Isotonic https://github.com/perellonieto/PyCalib/blob/master/pycalib/models/__init__.py#L552

This class should ideally accept any base calibrator and base probabilistic classfier.

However, it is not clear if this class is necessary, as it may be outdated by CalibratedModel https://github.com/perellonieto/PyCalib/blob/master/pycalib/models/__init__.py#L205