only use logger after logger configuration in jubavisor (fix #873)
only use logger after logger configuration in jubavisor (fix #873)

jubatus/jubatus,roselleebarle04/jubatus,jubatus/jubatus,elkingtonmcb/jubatus,elkingtonmcb/jubatus,jubatus/jubatus,gintenlabo/jubatus,rimms/jubatus,Asuka52/jubatus,mathn/jubatus,rimms/jubatus,mathn/jubatus,roselleebarle04/jubatus,gintenlabo/jubatus,Asuka52/jubatus