deps: Upgrade graceful-fs dependency to the latest

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

PR-URL: #45

Author: thefourtheye

package.json

@@ -12,7 +12,7 @@
     "node": ">=0.6"
   },
   "dependencies": {
-    "graceful-fs": "3",
+    "graceful-fs": "^4.1.2",
     "inherits": "~2.0.0",
     "mkdirp": ">=0.5 0",
     "rimraf": "2"