Only lint-readme on travis if Python 2.7

Doesn't work on 2.6, planemo has same hack.

.travis.yml

@@ -25,7 +25,7 @@ install:
   - pip install drmaa 
   - sudo adduser --quiet --disabled-password --gecos TEST u1  ## Create user for run-as-user test.  
 #  - sudo apt-get install condor
-script: export TEST_WEBAPP_POST_SHUTDOWN_SLEEP=1; . local_env.sh; make lint && make lint-docs && make lint-readme && make tests
+script: export TEST_WEBAPP_POST_SHUTDOWN_SLEEP=1; . local_env.sh; make lint && make lint-docs && if [[ $TRAVIS_PYTHON_VERSION == 2.6 ]]; then true; else make lint-readme; fi && make tests
 after_success:
   - coveralls