[NT-6] Serialize instance for EndpointAddress

[qnikst]

[Imported from JIRA. Reported by Rob Stewart @robstewartuk) as NT-6 on 2013-03-15 20:01:46] There is an instance for Binary from the binary package, for EndPointAddress: https://github.com/haskell-distributed/network-transport/blob/master/src/Network/Transport.hs#L132

It would be good to also have an instance for Serialize, for those users who use the cereal package for binary serialization. I might offer a merge request if I get time to do it and test it.