fix(package): update fs-extra to version 8.1.0

Closes #78

Author: greenkeeper[bot]

package.json

@@ -62,7 +62,7 @@
     "ethereum-ens": "0.7.4",
     "express": "4.16.4",
     "flat": "4.1.0",
-    "fs-extra": "7.0.1",
+    "fs-extra": "8.1.0",
     "github-api": "3.0.0",
     "helmet": "3.15.0",
     "js-yaml": "3.12.1",