validate range of pool_expire option (fix #620)
validate range of pool_expire option (fix #620)

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