chore(package): update eslint to version 5.15.1

Closes #63

Author: greenkeeper[bot]

package.json

@@ -33,7 +33,7 @@
   },
   "devDependencies": {
     "coveralls": "^3.0.0",
-    "eslint": "^4.13.1",
+    "eslint": "^5.15.1",
     "eslint-config-airbnb": "^16.1.0",
     "eslint-plugin-import": "^2.8.0",
     "eslint-plugin-jsx-a11y": "^6.0.3",