Player closure fix

[rogeralsing]

This PR fixes a non closed over Self reference in the Remote.TestKit Player.
Self is not safe to use in continuations as the Self property is pointing to the currently active context.

From ActorBase.cs

protected IActorRef Self { get { return HasBeenCleared ? _clearedSelf : Context.Self; } }

protected static IActorContext Context
{
      get
      {
         var context = InternalCurrentActorCellKeeper.Current;
         if (context == null)
            throw new NotSupportedException(
                        "There is no active ActorContext, this is most likely due to use of async operations from within this actor.");

         return context.ActorHasBeenCleared ? null : context;
     }
}

[Aaronontheweb]

Failure caused by the RemoteRoundRobinSpec, which is the usual suspect for failures