get project API

I need a remote API for fetching a project for a given repo that I can use in the browser directly.

This pull-request introduces a new API end-point `GET /:org/:repo/project`.

This is not the most gracious implementation, since I have to obtain the project access_level for the given current user..

The only way I found was to clone the project document and inject the `access_level` attribute computed on the `middleware.project` middleware.