Python 3 support, tox.ini, TravisCI build system.

[mpasternak]

IMPORTANT please remember this requires a recent pyoai. Release pyoai first, maybe.

[ulikoehler]

Maybe some of the maintainers (@jascoul / @infrae ?) could review and possibly merge this pull request? In the 5 years since this PR has been submitted, Python2.7 isn't supported any more and I would really appreciate if moai could update to Python 3.x.

[mpasternak]

I remember that I actually called @infrae offices. There was no answer back in the days, I don't exactly remember, 5 or 7 years ago.

@jascoul, if you're out there and willing to cooperate, I'm here.