Cross Version Operations

One of the primary goals of the SDK should be to abstract the concepts of different versions of an API from an end user. For example when a request is made to list projects the user should not care whether this happens over the V2 or V3 identity API.

This will require some architecture thought in terms of exposing an object that is API independent and correctly notifying a user when an operation they wish to perform simply cannot be exposed via the API options available to the SDK.

We will likely need an abstracted client object (i use 'client' there in the terminology of existing clients) that can handle the redirect to API specific calls - do we also need an abstracted object for every resource or is it sufficient to route calls from it back to the client for that abstraction?