BibFormat: fix issue in DataCite XSL

* Fixes an issue that caused invalid DataCite metadata documents
  to be created.

Signed-off-by: Lars Holm Nielsen <lars.holm.nielsen@cern.ch>
BibFormat: add display of all related identifiers

* Adds display of all related identifiers.

Signed-off-by: Lars Holm Nielsen <lars.holm.nielsen@cern.ch>