Use tox to run the tests on travis

.travis.yml

@@ -1,12 +1,12 @@
-# Configuration for Travis CI
-
 language: python
-python:
-  - "2.6"
-  - "2.7"
-  - "3.2"
-  - "3.3"
-  - "pypy"
-# command to run tests
+env:
+  - TOXENV=py26
+  - TOXENV=py27
+  - TOXENV=pypy
+  - TOXENV=py32
+  - TOXENV=py33
+  # - TOXENV=py34  # Travis-CI does not support 3.4 yet
+install:
+  - travis_retry pip install tox==1.6.1
 script:
-  - python setup.py test -q
+  - travis_retry tox