rework system initialization, remove remote address from LocalActorRef

- move all creation of ActorRefs into the ActorRefProvider (deadLetters,
  locker)
- rootPath does not contain remote transport address any longer in order
  to start the LocalActorRefProvider before the RemoteTransport; the
  transport address is inserted during serialization only, which enables
  us later to have more than one transport available for one actor
  system (maybe even needed for clustering)
- fix inheritance between DeadLetterActorRef and EmptyLocalActorRef
- document some start-up dependencies by reordering constructor code
- fix remote tests which used self.path for identifying remote actors
  (since that no longer includes the remote transport address)

akka-remote/src/main/scala/akka/remote/RemoteDaemon.scala

@@ -18,7 +18,7 @@ case class DaemonMsgWatch(watcher: ActorRef, watched: ActorRef) extends DaemonMs
  *
  * It acts as the brain of the remote that responds to system remote events (messages) and undertakes action.
  */
-class RemoteSystemDaemon(system: ActorSystemImpl, address: Address, _path: ActorPath, _parent: InternalActorRef, _log: LoggingAdapter)
+class RemoteSystemDaemon(system: ActorSystemImpl, _path: ActorPath, _parent: InternalActorRef, _log: LoggingAdapter)
   extends VirtualPathContainer(system.provider, _path, _parent, _log) {
 
   /**
@@ -52,7 +52,8 @@ class RemoteSystemDaemon(system: ActorSystemImpl, address: Address, _path: Actor
       message match {
         case DaemonMsgCreate(factory, path, supervisor) ⇒
           path match {
-            case ActorPathExtractor(`address`, elems) if elems.nonEmpty && elems.head == "remote" ⇒
+            case ActorPathExtractor(address, elems) if elems.nonEmpty && elems.head == "remote" ⇒
+              // TODO RK currently the extracted “address” is just ignored, is that okay?
               // TODO RK canonicalize path so as not to duplicate it always #1446
               val subpath = elems.drop(1)
               val path = this.path / subpath