IOError merged into OSError since Python 3.3
Workaround on the unicode in py2 and str in py3 difference.
Fix py2 py3 compatible with six.
Update .gitignore
Fix tests by less strict assertion in features.
Fix py code in feature files to support py2 and py3.
Fix py code in feature file with six.
Fix tests with six, now all features/* could pass.