Bug 4105: Add hasOwner param to EntityOwnershipListener#ownershipChanged

Bug 4105: Add hasOwner param to EntityOwnershipListener#ownershipChanged

OF clustering needs to know when the last candidate is removed for an
entity so it can clean up inventory. We decided to add a new param,
hasOwner, passed to EntityOwnershipListener#ownershipChanged to indicate if
there is at least one remaining candidate and current owner when a
controller node loses ownership. So if
wasOwner=true && isOwner=false && hasOwner=false, the OF code can
remove the device node from inventory.

To simplify the EntityOwnershipListener#ownershipChanged interface and
to allow for possible future parameters w/o breaking the interface, the
parameters are now encapsulated in an EntityOwnershipChanged DTO. There
already was the same EntityOwnershipChanged class in
sal-distributed-datastore - this class was removed.

Change-Id: I07375f154ac55d34062380ad6d0b30d970bd28e7
Signed-off-by: Tom Pantelis <tpanteli@brocade.com>