allow multiple independent services

[ggrandes]

GossipMonger gossipMonger = GossipMonger.getInstance("systemX");
Talker recv = new AbstractTalker(gossipMonger, "dummyReceiver") {
    @Override
    public void newMessage(final Whisper<?> whisper) {
        System.out.println(getName() + " Receive new whisper: "
                + whisper);
    }
};