Lint frontend in Travis.

This adds an ESLint step to the CI service so we prevent unlinted code from
making its way in.

Author: CM Lubinski

.travis.yml

@@ -9,10 +9,18 @@ env:
 cache:
   directories:
     - ~/.cache/pip
+    - ~/.nvm/nvm.sh
 install:
  - pip install tox
+ - curl -o- https://raw.githubusercontent.com/creationix/nvm/v0.33.2/install.sh | bash
+ - source ~/.nvm/nvm.sh
+ - nvm install --lts
+ - nvm use --lts
+ - npm install
+ - bower install
 script:
  - tox -e $TOX_ENV
+ - gulp lint
 notifications:
   slack:
     rooms: