Test Python 3.4 on travis.
Support new NameConstant node in filter AST.
Changelog update. [ci skip]
Add Python 3.4 to classifiers in setup script. [ci skip]
Do not require coverage for visit_NameConstant as it is Python 3.4+ only.
Merge pull request #66 from mcmtroffaes/feature/python34

Support Python 3.4.