Inherit Fraction in Ratio class, accounting for 0/0. (#72)
Inherit Fraction in Ratio class, accounting for 0/0. (#72)

* Inherit Fraction in Ratio class.

Pull request #53 had an issue with ZeroDivisonError. This version
overrides Fraction's __new__ function to account for that.

* _normalize not introduced until 3.5

ianare/exif-py