Eliminate glitch that caused job to be sent to deadletters, see #2630

* Cluster sample
* The problem was that the sent job was sometimes sent to deadLetters
* The reason was that statsService was not created when a facade
  at another node forwared the job to the statsService, i.e.
  deadLetters
* Solved by using ask and recover with JobFailed in case of
  timeout in the facade, so that the facade always sends back
  JobResult or JobFailed

akka-samples/akka-sample-cluster/src/multi-jvm/scala/sample/cluster/stats/StatsSampleSpec.scala

@@ -128,7 +128,7 @@ abstract class StatsSampleSpec extends MultiNodeSpec(StatsSampleSpecConfig)
       }
       meanWordLength must be(3.875 plusOrMinus 0.001)
 
-      testConductor.enter("done-2")
+      testConductor.enter("done-3")
     }