Lint JSX files and error on warnings

package.json

@@ -85,7 +85,7 @@
     "webpack-postcss-tools": "^1.1.1"
   },
   "scripts": {
-    "lint": "./node_modules/eslint/bin/eslint.js frontend/src",
+    "lint": "./node_modules/eslint/bin/eslint.js --ext .js --ext .jsx --max-warnings 0 frontend/src",
     "test": "./node_modules/karma/bin/karma start frontend/test/karma.conf.js --single-run --reporters nyan",
     "test-watch": "./node_modules/karma/bin/karma start frontend/test/karma.conf.js --auto-watch --reporters nyan",
     "test-e2e": "./node_modules/protractor/bin/webdriver-manager update && ./node_modules/protractor/bin/protractor frontend/test/protractor-conf.js",