[TASK] Add eslint enforcement to travis.yml

.travis.yml

@@ -1,6 +1,9 @@
 language: node_js
 node_js:
   - "0.10"
+before_script:
+  - npm install -g eslint
+  - eslint --reset -c ./eslintrc $(git --no-pager diff --name-only --relative FETCH_HEAD $(git merge-base FETCH_HEAD origin/HEAD) | grep "\.js$")
 script: MOCHA_REPORTER=tap npm test --coverage
 after_success:
 - npm run coveralls