logger middleware in bpframework.

$3

https://github.com/bpcloud/middleware

#### Setup.

``js
import { Application } from 'bpframework';
import * as middleware_logger from '@bpframework/middleware-log4js';

Application.use(middleware_logger.middleware)
Application.runKoa(...);
`

#### Config.

`properties
bp:
# feign client log (none, basic, headers, full).
feignLoggingLevel: full # full
# restController log (none, basic, headers, full).
restControllerLoggingLevel: full # full
# logger dir
loggerDir:
`


#### Usage.

`
getLogger().info(...);
``