Removing unused grunt module

Author: avoidwork

package.json

@@ -34,8 +34,7 @@
     "grunt-contrib-concat": "~0.1.3",
     "grunt-contrib-jshint": "~0.1",
     "grunt-contrib-nodeunit": "~0.1.2",
-    "grunt-contrib-watch": "~0.2",
-    "grunt-shell": "~0.2.1"
+    "grunt-contrib-watch": "~0.2"
   },
   "keywords": ["file", "filesize", "size", "readable", "filesystem"]
 }