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
Race between termination and actorFor, see #3234
Fix failing UnreachableNodeJoinsAgainSpec

* Shutting down test conductor controller is never a good idea
Merge pull request #1341 from akka/wip-UnreachableNodeJoinsSpec-patriknw

Fix failing UnreachableNodeJoinsAgainSpec
implement ResumeWriting, see #3200

also included:
- a complete rewrite of the TCP docs based on real/tested/working code
  samples
- an EchoServer implementation which handles all the edge cases,
  available in Java & Scala
- renamed StopReading to SuspendReading to match up with ResumeReading
- addition of Inbox.watch()
- Inbox RST docs for Java(!) and Scala

not included:
- ScalaDoc / JavaDoc for all IO stuff
Added acknowledged delivery of system messages
Fixed compile errors
Factory methods for Props

* cleanup of deprecated usage of Props in cluster sample
Merge pull request #1342 from akka/wip-props-factory-methods-patriknw

Factory methods for Props
Merge pull request #1340 from akka/wip-3234-ActorLookupSpec-patriknw

Race between termination and actorFor, see #3234
Merge pull request #1339 from akka/wip-3200-ResumeWriting-∂π

implement ResumeWriting, see #3200
Adding workaround for UnreachableNodeJoinsAgain

 - see #3247
Merge pull request #1338 from drewhk/wip-1478-sysmsg-guaranteed-delivery-drewhk

Guaranteed delivery of system messages (and now praying...)