Made travis use latest setuptools

This was casing problems since [#build54](https://travis-ci.org/fafhrd91/aiohttp/builds/14501366) which is directly linked with [setuptools-issue-131](https://bitbucket.org/pypa/setuptools/issue/131/test-failures-with-python33).

[Recetly](https://bitbucket.org/pypa/setuptools/src/tip/CHANGES.txt?at=default) setuptools got more bugfixes