Added a 'member' concept to projects.
members is the start of a basic project 'role' definition. In Helix sync, this is mostly just used to indicate this is a "my Project" in the UI and a project member can have the ability to leave the project or add someone else.
Eventually, we expect "members" to mean more, like, is part of a group that has write access to the files of the project. But that sort of definition is very TBD.