Fix deprecation use in the Actors Java Example on the Main Page

The Actors Java Example on the Main Page uses a [deprecated Props constructor]
(http://doc.akka.io/japi/akka/2.2.3/akka/actor/Props.html#Props(akka.actor.UntypedActorFactory)).
This commit makes use of the [Props.create(java.lang.Class, java.lang.Object...)]
(http://doc.akka.io/japi/akka/2.2.3/akka/actor/Props.html#create(java.lang.Class, java.lang.Object...)) static method.