Refactor "governor" roles

[shaunagm]

Instead of having a dedicated governor role, we could give owners the option of giving any custom role "default permission" - that is, the ability to do any non-foundational action by default. (This terminology needs to be fixed since we call pre-set permissions default permissions.)

Benefits:

• can create multiple kinds of governors with different permissions (so some people can do anything but just need approval, while others can do anything but don't need approval)
• is less in-your-face about the preset governance structure -- only owners are pre-defined (though it's not really any more hands off, just less obviously so)

Drawbacks:

• possibly more confusing, rather than less?
• work to refactor