Small fix for packaing metadata

Hi Ryan,

I was attempting to install python-zxcvbn using pip today, and it wasn't happy with your setup.py file. This new version works properly for me, but I'm not overly familiar with distutils. Feel free to pull this, or I can always keep using my fork if that breaks something else on your side.

BTW, thank you for this!

Yanick Dufresne
Lilikoi Data Inc.