Merge 1466640fb59007a1bc0940502c6e5000b01758be into cd819ae74bfc204c86f1b3d1588859ec8f7d8240

.travis.yml

   - export PATH=~/drivers:$PATH
   - ./manage.sh npm_packages
   - ./manage.sh update_dev_packages
-  - pip install codecov
+  - pip install codecov flake8
+before_script:
+  # stop the build if there are Python syntax errors or undefined names
+  - flake8 . --count --select=E901,E999,F821,F822,F823 --show-source --statistics
+  # exit-zero treats all errors as warnings.  The GitHub editor is 127 chars wide
+  - flake8 . --count --exit-zero --max-complexity=10 --max-line-length=127 --statistics
 script:
   - ./manage.sh styles
   - ./manage.sh grunt_build