Move content from akka-docs-new into akka-docs

Now the paradox documentation is no longer functional until we update akka-docs
to generate from paradox instead of sphinx

akka-docs/src/test/scala/tutorial_3/DeviceManager.scala

@@ -0,0 +1,51 @@
+/**
+ * Copyright (C) 2009-2017 Lightbend Inc. <http://www.lightbend.com>
+ */
+
+package tutorial_3
+
+import akka.actor.{ Actor, ActorLogging, ActorRef, Props, Terminated }
+import tutorial_3.DeviceManager.RequestTrackDevice
+
+//#device-manager-full
+object DeviceManager {
+  def props(): Props = Props(new DeviceManager)
+
+  //#device-manager-msgs
+  final case class RequestTrackDevice(groupId: String, deviceId: String)
+  case object DeviceRegistered
+  //#device-manager-msgs
+}
+
+class DeviceManager extends Actor with ActorLogging {
+  var groupIdToActor = Map.empty[String, ActorRef]
+  var actorToGroupId = Map.empty[ActorRef, String]
+
+  override def preStart(): Unit = log.info("DeviceManager started")
+
+  override def postStop(): Unit = log.info("DeviceManager stopped")
+
+  override def receive = {
+    case trackMsg @ RequestTrackDevice(groupId, _) =>
+      groupIdToActor.get(groupId) match {
+        case Some(ref) =>
+          ref forward trackMsg
+        case None =>
+          log.info("Creating device group actor for {}", groupId)
+          val groupActor = context.actorOf(DeviceGroup.props(groupId), "group-" + groupId)
+          context.watch(groupActor)
+          groupActor forward trackMsg
+          groupIdToActor += groupId -> groupActor
+          actorToGroupId += groupActor -> groupId
+      }
+
+    case Terminated(groupActor) =>
+      val groupId = actorToGroupId(groupActor)
+      log.info("Device group actor for {} has been terminated", groupId)
+      actorToGroupId -= groupActor
+      groupIdToActor -= groupId
+
+  }
+
+}
+//#device-manager-full