Proposed versioning approach for when a major release is planned

[bethesque]

Based on my reading of this article I think we should go with the suggestion in “Versioning in API design” of using an Accept-Version header. I think this will work well with our HAL approach, because it doesn't force us to change our content type, and it will allow us to use the same entrypoint resource "/" to fetch the HAL index. Most of the URLs will be the same in V2, so we won't need to change most of the paths (except for changing /pacticipants to /applications) and that will avoid adding unnecessary bloat to the URLs.

FYI, this is a list of all the changes I would like made to the Pact Broker in some major version release in the future. They probably won't ever get done 😆