travis: Add Python 3.4 to testing.

.travis.yml

@@ -2,6 +2,10 @@ language: python
 python:
     - 2.7
 
+before_install:
+    - sudo apt-get update -qq -y
+    - sudo apt-get install python3.4
+
 install:
     - pip install tox cython
     - cython --cplus msgpack/_packer.pyx msgpack/_unpacker.pyx

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = py26,py27,py32,py33,pypy
+envlist = py26,py27,py32,py33,py34,pypy
 
 [testenv]
 deps=