Essentially, let the skin developers change the skin to meet the requirements and be done with it. Don't make the users also have to edit localsettings.php after that fact. That's just silly.
- Do a check for all the elements we expect a skin to provide (since it should at least be functional at the point)
- Add a hook for the skin to register itself as definitely compatible (basically like the current approach, but moves the responsibility from the skin user to the skin developer)