[Aleph rest-dlf connector] Added possile cause of IOException & refactored a bit all services
[Aleph rest-dlf connector] Refactored LookupItemSetService a little bit
Particularly moved Token management within parsing bibRecIds into RestDlfConnector to increase effectivity.
Until now it was set to first parse all available items within bibRecId & then cut these to fit in MaxItemsCount
Now are being parsed only those needed.