Update to web-fs ^1.5.1 for the required mkdir mode fix

deathcap/web-fs@8736b9c

Author: deathcap

package.json

@@ -16,7 +16,7 @@
     "npm": "^2.5.0",
     "browserify": "^8.1.3",
     "wzrd": "^1.2.1",
-    "web-fs": "^1.5.0",
+    "web-fs": "^1.5.1",
     "brfs": "^1.3.0",
     "through": "^2.3.6"
   },