Add eslint

.travis.yml

@@ -10,5 +10,6 @@ notifications:
 after_success:
   - npm i sidekick
   - sidekick run --travis
+  - npm run lint
   - npm install codeclimate-test-reporter
   - codeclimate-test-reporter < __coverage__/lcov.info

package.json

@@ -15,7 +15,8 @@
     "jest": "^22.0.4"
   },
   "scripts": {
-    "test": "jest"
+    "test": "jest",
+    "lint": "./node_modules/.bin/eslint drivers/* controllers/*"
   },
   "jest": {
     "name": "pixdisp",