Add python 3 tag to setup.py

[ubershmekel]

Is it possible to add the "Programming Language :: Python :: 3" classifier to setup.py?

Here's pip for example: https://github.com/pypa/pip/blob/develop/setup.py

[minrk]

I think we were going to wait until master is installable on python 3, rather than the separate py3k repo. Should be done by 0.12, though

[takluyver]

It's already included in my big Python 3 pull request: https://github.com/ipython/ipython/pull/663/files#diff-15 , so it will happen when we merge that.