BUG-2091: notification NodeRemoved and processing queue

- NodeRemoved notification is now enqueued in the same way
  as other notifications so that original order will be preserved
  and "homeless" messages eliminated
- NodeUpdated must use the same way of delivery to MD-SAL in order
  to preclude state where during reconnect nodeAdded would arrive
  before nodeRemoved

Change-Id: Iede472870fac9ce12e7e5817c9b21967a2a43173
Signed-off-by: Michal Rehak <mirehak@cisco.com>
Merge "BUG-2091: notification NodeRemoved and processing queue"