NodeJS应用托管平台
https://devcenter.heroku.com/articles/getting-started-with-nodejs#dyno-sleeping-and-scaling
http://www.clovery.org/use-heroku-deploy-nodejs-application.html
http://www.gmarwaha.com/blog/2011/05/18/heroku-trouble-with-windows-and-ssh-keys/ 创建ssh-key
在heroku中使用WebSocket https://devcenter.heroku.com/articles/node-websockets