fix package name

Author: methane

.travis.yml

@@ -5,7 +5,7 @@ python:
 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
+    - sudo apt-get install -q python2.6-dev python2.7-dev python3.2-dev python3.3-dev
     - cython --cplus msgpack/_packer.pyx
     - cython --cplus msgpack/_unpacker.pyx