I want to host nbdime as a multi-tenant, stateless REST service. However the diff & merge APIs currently only support local paths or URLs as arguments. This requires either uploading the files to the server or hosting them publicly, both of which I want to avoid.

Proposed change:

Allow the diff & merge apis to take notebook json as arguments; i.e. for /api/diff the request JSON would now be:

{
    "base":   "filename.ipynb" | "http://your-domain/url/path" | json_notebook,
    "remote": "filename.ipynb" | "http://your-domain/url/path" | json_notebook
}

If the endpoint receives a dictionary for any of the arguments, it would interpret it as a notebook and use that directly.

Some kind of --disallow-notebook-paths server flag to disable passing a path or URL to the API would be good too, for security purposes.

I'm willing to make the changes for this, just looking for any feedback first.