XE-1283 : Deleted documents are public to anybody, so that anyone can reach old deleted documents (especially when you delete a whole private space)

Made documents and attachments recycle bins available to XWikiAdminGroup only.
XE-1283 : Deleted documents are public to anybody, so that anyone can reach old deleted documents (especially when you delete a whole private space)

Added rights check in the DeletedDocument API, making it impossible to users who didn't had rights to see the document to retrieve when it's been deleted.