Use ExchangeId everywhere

Rename Exchange.Id to ExchangeId and move it to the messages package
and then use it whenever an exchange should be identified.
Use Exchange.Parameters from ExchangeInfo
Use Exchange.BrokerInfo in ExchangeInfo
Remove unneeded genericity from PeerInfo class
Use Exchange.PeerInfo in ExchangeInfo
Use a complete Exchange and a Role in ExchangeInfo
Move ExchangeId back to common.exchange package
Merge pull request #193 from sortega/issues/41

Use common.exchange.Exchange