BUG-2288: implement DOMNotificationRouter

Implements DOMNotification(Publish)Service using LMAX Disruptor. The
disruptor is used internallly to transfer requests from publishers to
two-stage notification dispatch, where the frist stage takes care of
delivering events to subscribers and the second stage notifies the
futures.

Change-Id: I654d9d044e80b2a2ff6fd5b05ddceed4e79a4ebc
Signed-off-by: Robert Varga <rovarga@cisco.com>