tox/travis: Run tests on Python 3.4/3.5/3.6

.travis.yml

@@ -1,8 +1,9 @@
 sudo: false
 language: python
 python:
+  - "3.4"
   - "3.5"
-  - "3.6-dev"
+  - "3.6"
   - "nightly"
 install:
   - pip install -r requirements.txt

tox.ini

@@ -2,6 +2,7 @@
 envlist =
     py34,
     py35,
+    py36,
     coverage,
     #flake8,
     check-manifest