Added recording and reporting of job failure reasons.

objectstore/ArchiveRequest.cpp

objectstore/ArchiveRequest.hpp

objectstore/RetrieveRequest.cpp

objectstore/RetrieveRequest.hpp

objectstore/cta.proto

scheduler/ArchiveJob.cpp

scheduler/ArchiveJob.hpp

scheduler/OStoreDB/OStoreDB.cpp

scheduler/OStoreDB/OStoreDB.hpp

scheduler/RetrieveJob.cpp

scheduler/RetrieveJob.hpp

scheduler/SchedulerDatabase.hpp

scheduler/SchedulerTest.cpp

scheduler/testingMocks/MockArchiveJob.hpp

scheduler/testingMocks/MockRetrieveJob.hpp

...server/castor/tape/tapeserver/daemon/DiskReadTaskTest.cpp

tapeserver/castor/tape/tapeserver/daemon/DiskWriteTask.cpp

...erver/castor/tape/tapeserver/daemon/DiskWriteTaskTest.cpp

...r/castor/tape/tapeserver/daemon/MigrationReportPacker.cpp

...r/castor/tape/tapeserver/daemon/MigrationReportPacker.hpp