Log stderr and stdout to file

Depends on #32 
Similar to https://github.com/cargomedia/socket-redis/blob/master/lib/utils.js#L15

Add some debug logging.
Emm. It is configurable because we use log4js. https://github.com/vogdb/pulsar-rest-api/blob/issue-20/bin/log4js.json.
And what about my question?