Use system cython.

Author: methane

.travis.yml

@@ -6,7 +6,10 @@ python:
     - 3.3
 
 install:
-    - "pip install cython six --use-mirrors"
-    - "python setup.py install"
+    - sudo apt-get update -qq
+    - sudo apt-get install -q cython
+    - cython --cplus msgpack/_msgpack.pyx
+    - pip install six --use-mirrors
+    - python setup.py install
 
 script: "nosetests -w test"