+clu #3636 Revert join to uninitialized

* Revert the change introduced in
  https://github.com/akka/akka/pull/1738/files
* The cleanup/improvements aside of the actual
  feature is not reverted by this patch
* Clarify the documentation

akka-cluster/src/main/scala/akka/cluster/ClusterDaemon.scala

@@ -292,7 +292,6 @@ private[cluster] class ClusterCoreDaemon(publisher: ActorRef) extends Actor with
     case InitJoin                          ⇒ sender ! InitJoinNack(selfAddress)
     case ClusterUserAction.JoinTo(address) ⇒ join(address)
     case JoinSeedNodes(seedNodes)          ⇒ joinSeedNodes(seedNodes)
-    case Join(node, roles)                 ⇒ joiningUninitialized(node, roles)
     case msg: SubscriptionMessage          ⇒ publisher forward msg
   }
 
@@ -305,7 +304,6 @@ private[cluster] class ClusterCoreDaemon(publisher: ActorRef) extends Actor with
     case JoinSeedNodes(seedNodes) ⇒
       becomeUninitialized()
       joinSeedNodes(seedNodes)
-    case Join(node, roles)        ⇒ joiningUninitialized(node, roles)
     case msg: SubscriptionMessage ⇒ publisher forward msg
     case _: Tick ⇒
       if (deadline.exists(_.isOverdue)) {
@@ -473,16 +471,6 @@ private[cluster] class ClusterCoreDaemon(publisher: ActorRef) extends Actor with
     }
   }
 
-  /**
-   * Another node is joining when this node is uninitialized.
-   */
-  def joiningUninitialized(node: UniqueAddress, roles: Set[String]): Unit = {
-    require(latestGossip.members.isEmpty, "Joining an uninitialized node can only be done from empty state")
-    joining(node, roles)
-    if (latestGossip.hasMember(selfUniqueAddress))
-      becomeInitialized()
-  }
-
   /**
    * Reply from Join request.
    */