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](https://github.com/eslint/eslint/compare/v3.19.0...v4.18.2)

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

package.json

@@ -24,7 +24,7 @@
     "browserify": "^13.1.1",
     "chai": "^3.5.0",
     "del": "^2.2.2",
-    "eslint": "^3.10.2",
+    "eslint": "^4.18.2",
     "eslint-config-airbnb-base": "^10.0.1",
     "eslint-plugin-import": "^2.2.0",
     "gh-pages": "^1.1.0",