New data type for Eureka registry

Adding new data type for Eureka registry that stores multiple copies of instanceInfo data w.r.t. to different input sources
We do not need this information on client side, but I understand it must be there because we share the registry code with the server. However, we could make it more readable, by putting server address (host:port).
I would like to add server id concept, as depending on IPs to identify myself vs others is cumbersome. We have pending issue about that for Eureka 1.0 (https://github.com/Netflix/eureka/pull/119). It is purpose is to use in the replication channel, but once we have it, we could apply this more uniformly.