Adding python types

[sbdchd]

I was wondering if you'd be open to adding python types directly to the repo to support mypy and similar tools.

Since rure supports python 2.7 the comment based type hint syntax would be required: https://mypy.readthedocs.io/en/stable/python2.html

[davidblewett]

@sbdchd I'm actually not opposed to increasing the minimum Python version. I'm on the fence wrt mypy. I'm not using this library at work anymore, so haven't spent much time maintaining it. It's perfectly functional, but I don't have the cycles to do tasks like this. If you want to prepare a PR, I'll be happy to review it.