Facebook has further enhanced the Dev App by adding the ability to add and create Facebook Groups within the Developer App to manage users who are Administrators, Developers, Insights Users, and Testers in our apps. With this feature, adding users to a role across different apps has become much simpler, especially if you are working in a large team or company.
Right now, Facebook has made this feature available to a limited number of developers only. It should be released to the general public next week.
If you want to try to that, you can make a request in http://developers.facebook.com/blog/post/531/.