Add endpoints for project settings

[stevegore]

Not in documentation, but looking at how the front end works with the back end, this endpoint is clearly usable.

[levlaz]

Hello,

Thank you very much for this PR.

We used to have an experimental module to handle these sorts of things and I would propose to re-introduce this module if we are going to start to take advantage of "unofficial" parts of the API.

Since the undocumented API is subject to change at any moment (and has in the past) I think this makes a bit more sense so that end-users of this wrapper could at least keep in mind that anything in the experimental module is unstable.

What do you think?

[stevegore]

Sounds good to me!