make heroku happy by listen on PORT

app.json

 {
   "name": "Wechaty Cloud Bot for IO",
-  "description": "Wechat for Bot. Get your own cloud bot by deploy me on https://wechaty.io",
+  "description": "Wechat for Bot. Get your own cloud bot by deploy me",
   "repository": "https://github.com/zixia/wechaty",
   "logo": "https://raw.githubusercontent.com/zixia/wechaty/master/image/wechaty-icon.png",
   "keywords": ["wechaty", "wechat", "bot", "chatbot", "framework", "cloudbot"],

bin/io-bot.js

@@ -44,4 +44,19 @@ bot.init()
   log.error('Bot', 'init() fail: %s', e)
   bot.quit()
   process.exit(-1)
+})
+
+/**
+ *
+ * To make heroku happy
+ *
+ */
+const app = require('express')()
+
+app.get('/', function (req, res) {
+  res.send('Wechaty Deployed on Heroku Succeed!')
+})
+
+app.listen(process.env.PORT, function () {
+  console.log('Wechaty IO Bot listening on port ' + process.env.PORT + '!')
 })
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