Drop Python 3.2 Support

[Andrew Pinkham]

The TravisCI config file specifies testing environments for Python 2.7 and 3.4, but the tox config runs against 2.7, 3.2, and 3.4.

When tox is run, the Python 3.2 environment fails because behave no longer supports Python 3.2.

I am under the impression that captainhook no longer supports Python 3.2, and that tox should no longer be checking Python 3.2.

Note that tox is not actually in the requirements.txt or test_requirements.txt files, and that I am not actually sure tox is the recommended way to test captainhook.