Fix search for users who don't belong to members

If a user is not an admin nor part of "members", then search don't work (no results) even if the user has read permission on documents.
Once you add that user to members, then search returns the documents for which the user has read permission

How to reproduce:

• create a group 'consumers'
• create a user 'mika' and add it to consumers but not members
• set read permission for consumers on the root document
• log in with mika
• you can browse the repository but search (jsf or webui) does not return any results
• when adding permissions to the user or group locally, on a test workspace for instance, works correctly
• when removing these local permissions, it still works correctly (as if problem has been fixed by local permissions addition and removal)