fix(package): update commander to version 4.0.0

Closes #93

Author: greenkeeper[bot]

package.json

@@ -11,7 +11,7 @@
   },
   "dependencies": {
     "automutate": "0.5.X",
-    "commander": "^2.19.0",
+    "commander": "^4.0.0",
     "lesshint": "^5.3.0"
   },
   "devDependencies": {