fix(package): update commander to version 2.15.0 (#4611)

Author: greenkeeper[bot]

package.json

@@ -24,7 +24,7 @@
     "@parse/simple-mailgun-adapter": "1.0.1",
     "bcryptjs": "2.4.3",
     "body-parser": "1.18.2",
-    "commander": "2.14.1",
+    "commander": "2.15.0",
     "deepcopy": "0.6.3",
     "express": "4.16.2",
     "intersect": "1.0.1",