nearly done, only two known test failures

- moved typed actor factories to app/context (like actor factories)
- fixed a few misplaced supervision changes, all such tests green now
- actually test akka-reference.conf in ConfigSpec
- made DispatcherActorSpec more deterministic (failed intermittently
  here, was due to race towards thread pool)
- wrapped all actor initialization failures into
  ActorInitializationException and made sure that this leads to Stop
- default to Stop on ActorKilledException
- fixed ActorModelSpec to separately supervise the “waves of actors”
  because otherwise the app.guardian is way too busy processing all
  those ChildTerminated messages
- change ActorCell._children from Vector[Stats] to TreeMap[ActorRef,
  Stats] for performance reasons, have not measured memory impact, yet
- ensured that InterrupedException does not leave current thread via
  Failed message to supervisor (wrapped in ActorInterruptedException)
- set core-size=1 and max-size=4 for default dispatcher during test

project/AkkaBuild.scala

@@ -394,7 +394,7 @@ object AkkaBuild extends Build {
 object Dependencies {
   import Dependency._
 
-  val testkit = Seq(Test.scalatest)
+  val testkit = Seq(Test.scalatest, Test.junit)
 
   val actorTests = Seq(
     Test.junit, Test.scalatest, Test.multiverse, Test.commonsMath, Test.mockito,