Make the project structure more generic

I am working on a plugin to integrate with Gitlab. I think the "Projet" object is very opinionated and tied to d.o project structure. It would be great to not display the information on the frontend if no value is given. For example, "By undefined" should not be displayed if Author is not set.

I think the plugins will mainly be used to connect to private sources and so many information may not be available nor interesting in that situation.