Providing help for implementation of ProjectGroup object

[WH-Yoshi]

Hi, I'm a user of your library for a little RAG project. During my project which is still in development I needed to use the project groups that Polarion gives access to, so I created my implementation of a ProjectGroup object, for my personal use.

It's not complete but I followed kind of the same way as yours for an easy implementation.
Let me know if interested!