Add more python versions to test against.

Author: pglombardo

.travis.yml

@@ -1,6 +1,9 @@
 language: python
 python:
   - "2.7"
+  - "3.3"
+  - "3.4"
+  - "3.5"
   - "3.6"
 install: "pip install -r requirements.txt"
 script: nosetests -v