Allow users to associate themselves with multiple organizations

- A signed in user can go to an organization's public profile and add and/or remove roles from the organization regardless of whether the organization has been claimed or not (like a wiki)
- The organization admin user can remove any users that add themselves
- Associated organizations are shown on a user's public profile
- Various style and refactoring changes

TODO:
- Allow admin user to add users
- Allow users to add organizations from his or her profile
- Send admin user an email when a user associates him or herself with an organization