http://12factor.net/logs 里面提到：
A twelve-factor app never concerns itself with routing or storage of its **output stream**. It should not attempt to write to or manage logfiles. Instead, each running process writes its event stream, unbuffered, to stdout.
In staging or production deploys, each process’ stream will be captured by the execution environment, collated together with all other streams from the app, and routed to one or more final destinations for viewing and long-term archival.
这个意思是"我的代码中所有的Log.debug, Log.error都替换成print吗？"，感觉这样很别扭啊。。。