Bump eslint from 3.19.0 to 4.18.2

Bumps [eslint](https://github.com/eslint/eslint) from 3.19.0 to 4.18.2.
- [Release notes](https://github.com/eslint/eslint/releases)
- [Changelog](https://github.com/eslint/eslint/blob/master/CHANGELOG.md)
- [Commits](eslint/eslint@v3.19.0...v4.18.2)

Signed-off-by: dependabot[bot] <support@github.com>

package.json

@@ -28,7 +28,7 @@
   },
   "devDependencies": {
     "@staffbase/eslint-config-staffbase": "^0.1.1",
-    "eslint": "^3.19.0",
+    "eslint": "^4.18.2",
     "eslint-config-google": "^0.7.1",
     "highlight.js": "^9.12.0",
     "husky": "^0.13.4",