Add fs-extras to dev dependencies

Author: mauricerkelly

package.json

@@ -52,7 +52,8 @@
   "devDependencies": {
     "eslint": "^3.13.0",
     "eslint-config-airbnb-base": "^11.0.1",
-    "eslint-plugin-import": "^2.2.0"
+    "eslint-plugin-import": "^2.2.0",
+    "fs-extra": "^3.0.1"
   },
   "eslintConfig": {
     "extends": "airbnb-base",