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.