API to Upload Notebook

[GordonSmith]

Could we get an official API to upload an entire Notebook?

Bonus marks for an API to publish / unpublish / share / unshare.

Something along the lines of:

{
    "title": "A Taste of Observable",
    "nodes": [
        {
            "value": "md`# Hello and Welcome!`",
            "pinned": false
        },
        {
            "value": "mol = 42",
            "pinned": false
        }
    ]
}