add enum34 dependency to tox

Author: Michael Davis

.travis.yml

@@ -1,7 +1,7 @@
 sudo: false
 # Travis infra requires pinning dist:precise, at least as of 2017-09-01
 # detail: https://blog.travis-ci.com/2017-06-21-trusty-updates-2017-Q2-launch
-dist: precise
+dist: trusty
 language: python
 python:
   - "2.6"
@@ -12,7 +12,7 @@ python:
   - "3.6"
   - "pypy-5.3.1"
 install:
-  - pip install -U tox codecov tox-travis
+  - pip install -U setuptools && pip install -U tox codecov tox-travis
 script:
   - tox
 after_success:

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = py{26,27,33,34,py}
+envlist = py{27,33,34,35,36,37,py,pypy}
 
 [testenv]
 commands =
@@ -12,4 +12,5 @@ deps =
     pytest-cov
     pytest-runner
     cryptography
-
+    enum34
+    six