remove unused method from header (fix #917)
remove unused method from header (fix #917)

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