Merge pull request #687 from fuxiaohei/develop

code style simplify
Merge pull request #689 from fuxiaohei/develop

code style simplify
Issue #682: convert logs package to RFC5424 logging levels.
Merge pull request #691 from FGM/logger-rfc5424

Issue #682: convert logs package to RFC5424 logging levels.
Merge remote-tracking branch 'remotes/astaxie/develop' into develop