[NEW] Add lint command (RocketChat#551)

Author: vcapretz

package.json

@@ -81,6 +81,7 @@
     "start": "gulp start",
     "pretest": "gulp build-unit --env=test",
     "test": "electron-mocha app/specs.js.autogenerated --renderer --require source-map-support/register",
+    "lint": "eslint .",
     "coverage": "npm test -- -R scripts/istanbul-reporter",
     "pree2e": "gulp build-e2e --env=test",
     "e2e": "mocha app/e2e.js.autogenerated --require source-map-support/register"