Extend travis-ci tests with Python 3.2 and 3.4 env.

I know it's not changing a lot, but there's still a community using python 3.2 (shame for them)... and finally should start supporting 3.4 version - Travis currently uses bugfixed [3.4.1 version](http://blog.travis-ci.com/2014-07-24-upcoming-build-environment-updates/).
implicit `del` should be fine