Make installable via pip

[rzurad]

Greetings!

This PR adds a setup.py file so that this project can be installed via pip and used as a dependency in other python projects.

I don't spend a lot of time in Python-land, so this is the first setup.py I've ever had to create. If I forgot something or am doing something stupid, please let me know. I also didn't want to clobber version 2.0 since that's an already tagged release that isn't importable by pip, so I just assigned the version as 2.1a1.

Let me know if you need anything else from me. Thanks!

[googlebot]

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[rzurad]

I signed it!

[googlebot]

CLAs look good, thanks!

[rzurad]

No, googlebot, thank you! 👯

[suderman-google]

Sorry for the delay. Thanks for the fix and we are happy to accept :)