Ambiguous name for 'add_base_attribute' method.

[kritchie]

The method 'add_base_attribute' is a little bit ambiguous. It doesn't 'add' attributes but replaces the self.attributes with the content passed to the method.

I suggest two options :

1. Change the name of the method
2. Change the method to 'add' to the self.attributes instead of replacing the dict completely.

I prefer option [1] but it should be more explicit. This would let the user of the class to have more freedom on what they want to set as parameters.

I can propose a PR for that if it's accepted and no one else is free to work on that.