[dependencies] Remove unnecessary dependencies

Author: slyg

package.json

@@ -24,18 +24,14 @@
     "esprima": "1.2.2",
     "glob": "4.3.1",
     "handlebars": "1.3.0",
-    "lodash": "2.4.1",
-    "walk": "2.3.3"
+    "lodash": "2.4.1"
   },
   "devDependencies": {
     "chai": "1.10.0",
     "chai-as-promised": "4.1.1",
     "coffee-script": "^1.8.0",
     "grunt": "0.4.5",
     "grunt-contrib-jshint": "0.10.0",
-    "grunt-exec": "0.4.6",
-    "grunt-istanbul": "0.2.4",
-    "grunt-istanbul-coverage": "0.0.5",
     "mocha": "2.0.0"
   },
   "scripts": {