Results 9 issues of Roy Keyes

Options: - Refactor type hints for 3.5 compatibility - Remove 3.5 support

bug

We need tests! - I am planning to use [pytest](http://pytest.org). - Asymptotic tests would be nice for the MAB strategies.

enhancement

`slots.py:377: RuntimeWarning: invalid value encountered in true_divide sum(self.pulls) * np.max(np.nan_to_num(self.wins / self.pulls))`

bug
minor