update memory-fs dep

Author: SpaceK33z

package.json

@@ -7,7 +7,7 @@
     "webpack": "1 || ^2.1.0-beta"
   },
   "dependencies": {
-    "memory-fs": "~0.3.0",
+    "memory-fs": "~0.4.1",
     "mime": "^1.3.4",
     "path-is-absolute": "^1.0.0",
     "range-parser": "^1.0.3"