fix(package): update commander to version 4.0.1

Closes #41

Author: greenkeeper[bot]

package.json

@@ -66,7 +66,7 @@
     "typescript-formatter": "^7.2.2"
   },
   "dependencies": {
-    "commander": "^2.19.0",
+    "commander": "^4.0.1",
     "shelljs": "^0.8.3"
   },
   "nyc": {