chore(package): update qs to version 6.2.1 (#48)

https://greenkeeper.io/

Author: greenkeeperio-bot

package.json

@@ -103,7 +103,7 @@
     "lru-cache": "^4.0.1",
     "mime": "^1.3.4",
     "once": "^1.3.2",
-    "qs": "^5.2.0",
+    "qs": "^6.2.1",
     "restify-errors": "^4.2.3",
     "vasync": "^1.6.3"
   }