Support Python 3

[sylvanbytes]

Please consider supporting python 3 in future versions.

[euangoddard]

We'd be happy to consider a patch if you would like to write one.

[jirikuncar]

@euangoddard Can you have a look at #16, please?

[trcull]

Hey guys, as the deadline looms for Jan 1, I'm finding that this project and one other project (according to caniusepython3) are my only barriers. Are there plans to support Python 3?

[jirikuncar]

@trcull check #16 (comment)