use WatchedFileHandler to better handle log rotation of forseti.log (#2994)
use WatchedFileHandler to better handle log rotation of forseti.log (#2994)

* use WatchedFileHandler to better handle log rotation of forseti.log

* fix lint issue

forseti-security/forseti-security,forseti-security/forseti-security,forseti-security/forseti-security,forseti-security/forseti-security