engine : User can see events which don't belong to him

User can see events which are not related to objects he
has permissions on.

This patch introduces a new view user_object_permissions_view
which has the object on which the user has been granted permissions
on and uses it for retrieving the events.

Change-Id: I7b7a6691f6cfa2ca1c0d0d90294ecd93781fce38
Bug-Url: https://bugzilla.redhat.com/921274
Signed-off-by: Ravi Nori <rnori@redhat.com>