=clu #3498 Optimize ClusterHeartbeatSender
!clu #3599 Use counter in VectorClock

* No reason to use the System.currentTimeMillis base
* Remove the global VectorClock counter completely,
  current count for a node is in the VectorClock itself
Merge pull request #1726 from akka/wip-3498-optimize-heartbeat-sender-patriknw

=clu #3498 Optimize ClusterHeartbeatSender
Merge pull request #1722 from akka/wip-3599-vclock-counter-patriknw

!clu #3599 Use counter in VectorClock
3615 - InvalidActorNameException in persistence tests fixed

- use overridden processor and channel ids
- no need anymore to wait for processor instances to stop
- unrelated: fix wrong artifact names in documentation