Add versioneer for automated versioning

[Michael-F-Bryan]

It would be nice to include versioneer so that instead of manually needing to update version numbers in 4 or 5 separate places the version number is derived from git tags automatically.

This would prevent people from forgetting to update version numbers and also ensure that they follow a standard tagging scheme.

I believe the changes required would be minimal. I haven't made any cookie cutter templates before, but versioneer is really easy to set up and the instructions are quite thorough.

[Michael-F-Bryan]

Sorry, I didn't realize you were already using bumpversion for versioning instead.