Treat deleted OAI-PMH records well

Treat deleted OAI-PMH records correctly, e.g. http://dspace.wbv.de:8888/oai/request?verb=ListIdentifiers&metadataPrefix=xoai lists an identifier oai:dspace.wbv.de:103278/523, but querying for that identifier http://dspace.wbv.de:8888/oai/request?verb=GetRecord&metadataPrefix=xoai&identifier=oai:dspace.wbv.de:103278/523 results in a The given id does not exist error message.

DDA should filter out such records, possibly marking them as DELETED in the BundleEntity