Consider replacing our validators with voluptuous

https://github.com/alecthomas/voluptuous

Despite the name, it's a data validation library that does everything we need, and more. Its range even lets you specify if the ends should be included as valid or not (fixes another issue if I remember correctly).

As of February, many of the validators are classes just like ours, so our use-cases are 100% covered. What do you think? Worth dropping util/data.py for it?

Mapping:
Range -> Range
MatchesRegex -> Match
Equals -> Match or Range