Fix tox env once and for all

.travis.yml

@@ -6,10 +6,9 @@ python:
   - 3.5
 
 install:
-  - pip install -e .
-  - pip install tox flake8
+  - pip install tox
 
 script:
-  - tox -r -e py
+  - tox -e py
 
 sudo: false

tox.ini

@@ -1,12 +1,11 @@
 [tox]
 envlist = py33, py34, py35
 
-[base]
+[testenv]
 deps =
   flake8
   pytest
 
-[testenv]
 commands =
   flake8
   py.test