added pypy3 to travis and tox config

.travis.yml

@@ -4,6 +4,7 @@ python:
   - "3.4"
   - "2.7"
   - "pypy"
+  - "pypy3"
 
 # command to install dependencies, e.g. pip install -r requirements.txt --use-mirrors
 install: pip install -r requirements-dev.txt

tox.ini

@@ -1,6 +1,6 @@
 [tox]
 envlist =
-    py27, py34, pypy
+    py27, py34, pypy, pypy3
 
 [testenv]
 setenv =