Greenwire: Billionaire Tom Steyer isn't well-known outside California, but plenty of people believe that's about to change. He's seen here as a likely star in energy politics. Steyer, 55, is a self-made mogul who made a bundle as a hedge fund manager. He's also a philanthropist, environmentalist and father of four who says the country needs a clean energy revolution. He's spent part of his wealth working toward that aim. Last year, Steyer bankrolled a successful California ballot measure that will spend as...