chore(package): update eslint-config-airbnb to version 18.0.0

Closes #7

Author: greenkeeper[bot]

package.json

@@ -39,7 +39,7 @@
     "enzyme": "^3.1.0",
     "enzyme-to-json": "^3.1.2",
     "eslint": "^4.8.0",
-    "eslint-config-airbnb": "^16.0.0",
+    "eslint-config-airbnb": "^18.0.0",
     "eslint-plugin-import": "^2.7.0",
     "eslint-plugin-jsx-a11y": "^6.0.2",
     "eslint-plugin-react": "^7.4.0",