(Un)versioned URLs

[ml-evs]

We should start tracking Materials-Consortia/OPTIMADE#290 and discuss how we want to deal with it in the server code.

The PR will introduce the following:

• ability to use unversioned base URL to serve API, which should be the default in the schema we generated (see @rartino's comments in Update schemas for v1.0.0  OPTIMADE#294 (comment)
• requirement of a new /versions endpoint

At the very least, this is going to change how the validator needs to work. If given an unversioned base url, the validator needs to check for a /versions endpoint, so we probably need to add a flag to allow for versioned URLs to be tested without having to provide the /versions endpoint.

[ml-evs]

In fact, its just been merged, so we better get a move on!

[rartino]

Will you actually handle /versions, given that it does not respond with json?

Edit: Ah, sorry, I was thinking for the schemas. But of course the implementation needs to provide the endpoint!

[ml-evs]

Will you actually handle /versions, given that it does not respond with json?

Edit: Ah, sorry, I was thinking for the schemas. But of course the implementation needs to provide the endpoint!

I've implemented it in #380 in such a way that it does not appear in the schema; I think there is some argument to made that the versions endpoint should appear in the schema, but I'm not sure of the appropriate way to represent it...

[CasperWA]

Has this been closed by #380 or are there still things to double check?

[ml-evs]

Closed by #380.