I don't know, but I don't think Hulk should be viewed as a hero in the movie-verse personally. He should be heroic in his way, and the audience should see that of course, but it should go unappreciated by his fellow superpeople and the public generally IMO. That makes the character more interesting. He really has no business being on the Avengers team again, though I suspect he'll get shoved in there due to his success in the first film. Hulk doesn't make sense as a team member unless you are talking a team of genuine misfits like the Defenders. Lee and Kirby realized this right away.