fix(package): update commander to version 2.20.0

Author: greenkeeper[bot]

package.json

@@ -15,7 +15,7 @@
     "curl-trace-parser": "bin/curl-trace-parser"
   },
   "dependencies": {
-    "commander": "2.19.0",
+    "commander": "2.20.0",
     "api-blueprint-http-formatter": "0.0.1",
     "http-string-parser": "0.0.6"
   },