New Maintainer for this Package + Repo

I'm adding @schorrm as a collaborator for both this repo and its associated PyPI project. Moshe has been active in using and improving the package both here and in his [fork](https://github.com/schorrm/pybaseball). Having a more active maintainer and keeping most users under a single PyPI installation will be good for the quality and stability of the project. I'm excited to have him on board!