Remove dangling 2.6 reference, simplify test script clause. Closes #150

Had left a dangling reference to 2.6 that showed up on travis-ci web
page report.

The test script section was only different for 2.6.  Versions 2.7 and 3.3 are
the same (and 3.4 should be the same when it arrives).  That section can
now be simplified.

.travis.yml

@@ -1,6 +1,5 @@
 language: python
 python:
-  - "2.6"
   - "2.7"
   - "3.3"
 
@@ -17,8 +16,7 @@ install:
 
 # command to run tests
 script:
-  - if [[ $TRAVIS_PYTHON_VERSION == '2.7' ]]; then python -m unittest discover; fi
-  - if [[ $TRAVIS_PYTHON_VERSION == '3.3' ]]; then python -m unittest discover; fi
+  - python -m unittest discover
 
 notifications:
   email: "john.g.evans.ne@gmail.com"