#533: added support for sleep time to object store.

objectstore/RepackRequest.cpp

objectstore/RetrieveQueue.cpp

objectstore/RetrieveQueue.hpp

objectstore/RetrieveQueueAlgorithms.hpp

objectstore/RetrieveQueueToTransferAlgorithms.cpp

objectstore/cta.proto

scheduler/OStoreDB/OStoreDB.cpp

scheduler/OStoreDB/OStoreDB.hpp

scheduler/Scheduler.cpp

scheduler/SchedulerDatabase.hpp

scheduler/SchedulerDatabaseTest.cpp

scheduler/SchedulerTest.cpp

xroot_plugins/XrdCtaDiskSystemLs.hpp

xroot_plugins/XrdSsiCtaRequestMessage.cpp

xrootd-ssi-protobuf-interface