deps: update graceful-fs dependency to the latest

graceful-fs used to monkey-patch node's core fs module.
This has been fixed in version 4.

PR-URL: #714
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com>

package.json

@@ -24,7 +24,7 @@
   "dependencies": {
     "fstream": "^1.0.0",
     "glob": "3 || 4",
-    "graceful-fs": "3",
+    "graceful-fs": "^4.1.2",
     "minimatch": "1",
     "mkdirp": "^0.5.0",
     "nopt": "2 || 3",