fix(package): update commander to version 5.1.0

Closes #13

Author: greenkeeper[bot]

package.json

@@ -13,7 +13,7 @@
     },
     "dependencies": {
         "bluebird": "~3.5.2",
-        "commander": "~2.19.0",
+        "commander": "~5.1.0",
         "debug": "~4.1.0",
         "detect-indent": "~5.0.0",
         "inquirer": "~6.2.0",