chore(package): update nodeshift to version 1.8.1

Closes #102

Author: greenkeeper[bot]

Diff for: package.json

@@ -56,7 +56,7 @@
   "devDependencies": {
     "coveralls": "^3.0.0",
     "js-yaml": "^3.10.0",
-    "nodeshift": "~1.7.0",
+    "nodeshift": "~1.8.1",
     "nsp": "~3.2.1",
     "nyc": "~11.8.0",
     "proxyquire": "^2.0.0",