Bug 7746: Fix intermittent EOS test failure and synchronization

Bug 7746: Fix intermittent EOS test failure and synchronization

Modified the EntityOwnershipListenerSupport class to be thread-safe
utilizing a ReadWriteLock to guard access to the listenerActorMap
and entityTypeListenerMap. While updates are only done by the
EntityOwnershipShard and thus aren't concurrent, read access occurs
concurrently via the EntityOwnershipChangeListener which runs in its
own actor sandbox. I also factored out an
EntityOwnershipChangePublisher interface with the read-only access
methods used by EntityOwnershipChangeListener to make it clear
that EntityOwnershipShard is the only mutator.

The testFunctionalityWithThreeNodes case failed intermittently b/c
it's possible for the follower2MockListener to get notified of a
pre-existing entity on registration twice if the prior owner change
is replicated and the EntityOwnershipChangeListener triggers concurrently
with the registration and the timing is just right. I added verification
of ownership sync to follower2 pior to registration to make it
deterministic and avoid the sporadic timing failures.

Change-Id: Icc197d0c23135ca69b56eac1702f249e8e60e66e
Signed-off-by: Tom Pantelis <tpanteli@brocade.com>