Make string_vector_holder noncopyable.
Make string_vector_holder noncopyable.

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