`self.contributors` makes an API request to github, right? (it's delegated to github_grabber)
This is a bit confusing. `self.users` are the users who contributed to the project, but are fetched from the db, and `self.contributors` are contributors according to github.

I would probably change it to `fetch_contributors`, just to differentiate that from activerecord relations and to signify that it might be an expensive operation.