remove unneeded deep copy of unlearner_parameter
remove unneeded deep copy of unlearner_parameter

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