This will protect the server from non NATS clients (telnet, etc),
or misbehaving clients that would create the tcp connection but
block before sending the CONNECT.
The drawback is that the client may or may not receive the error
message (in my tests, it was getting only between 10%-20% of times).
Clients that will be at the ClientProtoInfo protocol level (or above)
will now receive an asynchronous INFO protocol when the server
they connect to adds a *new* route. This means that when the cluster
adds a new server, all clients in the cluster should now be notified
of this new addition.
