Serializer configuration support

Serailizers are no longer hardcoded into the `Serialization` class.
We are now using the correct config sections:

```json
akka.actor {
    serializers {
        acme = "Acme.Inc.MySerialier"
	}

    serialization-bindings {
      ""Acme.My.MessageType"" = acme 
    }
}
```