[logback] log4j -> logback 마이그레이션

링크: http://allbegray.tistory.com/11

logback configuration: http://logback.qos.ch/manual/configuration.html

logback-ext-spring: https://github.com/qos-ch/logback-extensions/wiki/Spring

log4j.properties -> logback.xml convert: http://logback.qos.ch/translator/

logback을 사용해야 하는 이유: http://beyondj2ee.wordpress.com/2012/11/09/logback-%EC%82%AC%EC%9A%A9%ED%95%B4%EC%95%BC-%ED%95%98%EB%8A%94-%EC%9D%B4%EC%9C%A0-reasons-to-prefer-logback-over-log4j/

log4j -> logback으로 마이그레이션 하기: http://beyondj2ee.wordpress.com/2013/11/05/log4j%EC%97%90%EC%84%9C-logback%EC%9C%BC%EB%A1%9C-%EB%A7%88%EC%9D%B4%EA%B7%B8%EB%A0%88%EC%9D%B4%EC%85%98-%ED%95%98%EA%B8%B0-migrate-from-log4j-to-logback/

참고: http://ddakker.tistory.com/294