Versioning + Public changelog

[mprpic]

The cve-services app keeps a version string in package.json and the API has a different version itself. Neither of these version strings are exposed over any of the endpoints so it's not clear which one is the true version number against which you can claim any compatibility with clients. On top of that, the Git tags in the repo don't reflect either of these versions since the only existing one is v1.0.

Assuming the app uses semantic versioning, its version then reflects changes in the API, meaning both the app's version and the API's version could be the same. Git tags could mirror that version for an easier-to-navigate revision history.

I think it would also be nice to publish a versioned changelog with a list of user/client-impacting changes.

Wdyt?