Reliable remote supervision and death watch, see #2993

* 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
Merge pull request #1323 from akka/wip-2993-remote-watch-patriknw

Reliable remote supervision and death watch, see #2993