Add broker cluster peer port by default when network_peers is specified

[serialh0bbyist]

This should satisfy #252

[serialh0bbyist]

I also formatted some of the if and unless statements based on whether or not they were nested in the erb template.

[ripienaar]

Unfortunately its not this easy, you can have a broker with no declared peers, with its port open, thats a valid configuration.

In a setup like above if a new broker connects to this broker that has no known peers it will solicit the peer list from this new incoming peer and connect to them all. They also gossip the topology continuesly to keep this going, so you can have say 2 seed brokers and any number of unconfigured ones that learn the topology without configuration. We dont use it this way in the puppet modules, but its supported.

So we need something like (psuedo code):

if len(peers) > 0 {
   if peer_port == 0 {
     peer_port = 4223 // default port
   }

   configure_peer_port
   configure_peers
} else if peer_port > 0 {
   configure_peer_port
}