* The problem was a race caused by HeartbeatReq sent out, and
the watchee terminated immediately. That caused the RemoteWatcher
peers watching each other without any other watch registered.
It is racy.
* Instead of one-way heartbeats from the side beeing watched I
changed to ping-pong style. That makes the problem go away
and simplifies a lot of things in RemoteWatcher.
* UnreachableNodeJoinsAgain failed because of gated connection
* Removed default test value of retry-gate-closed-for, instead
default from reference.conf is used, i.e. 0s
* deadLetters logging love
* RemoteWatcher that monitors node failures, with heartbeats
and failure detector
* Move RemoteDeploymentWatcher from CARP to RARP
* ClusterRemoteWatcher that handles cluster nodes
* Update documentation
* UID in Heartbeat msg to be able to quarantine,
actual implementation of quarantining will be implemented
in ticket 2594
