Use tox on Travis.

Author: methane

.travis.yml

@@ -1,16 +1,12 @@
 language: python
 python:
-    - 2.6
     - 2.7
-    - 3.2
-    - 3.3
 
 install:
     - sudo apt-get update -qq
     - sudo apt-get install -q cython
+    - sudo apt-get install -q python26-dev python27-dev python32-dev python33-dev
     - cython --cplus msgpack/_packer.pyx
     - cython --cplus msgpack/_unpacker.pyx
-    - pip install six --use-mirrors
-    - python setup.py install
 
-script: "nosetests -w test"
+script: "tox"