fix(package): update commander to version 5.1.0

Closes #46

Author: greenkeeper[bot]

package.json

@@ -33,7 +33,7 @@
     "cheerio": "^1.0.0-rc.3",
     "co": "^4.6.0",
     "colors": "^1.3.3",
-    "commander": "^4.0.0",
+    "commander": "^5.1.0",
     "inquirer": "^7.0.0"
   },
   "devDependencies": {