Remove/freeze python 3.2

[mattrobenolt]

Lots of python libraries are dropping support for python 3.2.

Specifically, virtualenv 14.0.0 (https://virtualenv.pypa.io/en/latest/changes.html) and pip 8.0.0 (https://pip.pypa.io/en/stable/news/).

urllib3 has dropped 3.2: urllib3/urllib3#787 This means that requests (https://github.com/kennethreitz/requests) will be dropping 3.2 since it depends on urllib3.

So given that this is the trend, I propose we either remove 3.2 from here, or explicitly lock it so dependencies don't get updated like in #83.

[yosifkit]

👍 We were planning to drop it once it hit end of life, which should be February 2016. So a freeze for now is perfectly reasonable.

[tianon]

Oh, EOL is literally next month -- why not just drop it? Is there any way to know whether a final "goodbye" release is planned?

[alex]

There's no final release planned to the best of my knowledge.

[tianon]

Cool, thanks @alex ❤️

Let's axe it. 👍