document Specs2 + TestKit, see #2068, plus fix up broken includes

- include move of doc samples out of akka package also in the
  includecode directives
- fix broken serialization docs, which require one thing in the akka
  package

akka-docs/scala/code/docs/testkit/Specs2DemoAcceptance.scala

@@ -0,0 +1,34 @@
+package docs.testkit
+
+import org.specs2._
+import org.specs2.specification.Scope
+
+import akka.actor.{ Props, ActorSystem, Actor }
+import akka.testkit.{ TestKit, ImplicitSender }
+
+class Specs2DemoAcceptance extends Specification {
+  def is =
+
+    "This is a specification of basic TestKit interop" ^
+      p ^
+      "A TestKit should" ^
+      "work properly with Specs2 acceptance tests" ! e1 ^
+      "correctly convert durations" ! e2
+
+  val system = ActorSystem()
+
+  implicit def d2d(d: org.specs2.time.Duration): akka.util.FiniteDuration =
+    akka.util.Duration(d.inMilliseconds, "millis")
+
+  def e1 = new TestKit(system) with Scope with ImplicitSender {
+    within(1 second) {
+      system.actorOf(Props(new Actor {
+        def receive = { case x ⇒ sender ! x }
+      })) ! "hallo"
+
+      expectMsgType[String] must be equalTo "hallo"
+    }
+  }
+
+  def e2 = ((1 second): akka.util.Duration).toMillis must be equalTo 1000
+}