CABINET: pubs with same ISBN are no longer considered same

- Publications with same ISBN are not considered same anymore.
  It caused confusion to users, when they were automatically added
  as authors of someone's else publication.
  It's common, that reported publication is in fact an article in
  publication, so many reports can have same ISBN.
Merge pull request #315 from zlamalp/publications

CABINET: pubs with same ISBN are no longer considered same