Merge pull request #226 from wechaty/greenkeeper/ws-2.0.0

Update ws to the latest version 🚀

package.json

@@ -114,7 +114,7 @@
     "retry-promise": "1.0.0",
     "selenium-webdriver": "3.0.0",
     "socket.io": "1.5.0",
-    "ws": "2.0.0-beta.1"
+    "ws": "2.0.0"
   },
   "devDependencies": {
     "@types/body-parser": "0.0.33",