Merge pull request #166 from NiteshKant/2.x

Removing the unused Index enum.
Adding an initial impl of InstanceLocation.
Adding a way to retrieve an eventual snapshot of current registry.
Adding instanceLocation to InstanceInfo.toString, equal, hascode etc.
Merge pull request #167 from qiangdavidliu/2.x

Initial naive implementation of InstanceLocation
Merge branch '2.x' of https://github.com/Netflix/eureka into 2.x