Use python 2.6 in travis-ci as python 2.5 don't work anymore.

5e382bea · Frederic · 43a594ad · 5e382bea
--- a/.travis.yml
+++ b/.travis.yml
@@ -3,7 +3,7 @@

 language: python
 python:
-  - "2.5"
+  - "2.6"
 #  - "2.7"
 #  - "3.2"
 # command to install dependencies