Improve performance and avoid strange issue with failing fq with not value for the read field
DS-1711 DS-1712 DS-1466 implement consistent definition of private item
Add browse private items link for administrators
Avoid exposure of private items over OAI-PMH
Added item.update() to set discoverable flag
Merge pull request #367 from zuki/private-items

Added item.update() to set discoverable flag
Merge pull request #360 from DSpace/private-items

DS-1711 DS-1712 DS-1466 Implement consistent definition of Private items