NG: HTTP rest API

[dmp42]

Describing here what we expect from the http API.

Should be:

• simpler than v1
• properly "namespace" layer access "under" repositories, in order to simplify access-control
• provision for both push and pull byte-range support
• cool ideas like from here: Registry next generation #612 (comment)

This is not about authentication or backend storage.

[dmp42]

This is going in docker main, since for now this is the contact surface with the engine and its super important to get good feedback from the engine perspective.

Thanks @stevvooe !!

moby/moby#9015 (comment)