Release v0.5.0 (#98)

diff --git a/tox.ini b/tox.ini
index ad760bd..2347bc1 100644
--- a/tox.ini
+++ b/tox.ini
@@ -70,7 +70,7 @@
 commands = make -C docs html
 
 [testenv:lint]
-basepython = python3.5
+basepython = python3.4
 commands =
   python setup.py check --metadata --restructuredtext --strict
   flake8 \