content generation for xml and json

[francescoagati]

format xml and json should not be wrappe in html like this:

[{"book":{"created_at":"2011-06-24T10:11:17Z","description":null,"id":1,"title":"book1","updated_at":"2011-06-24T10:11:17Z"}},{"book":{"created_at":"2011-06-24T10:11:17Z","description":null,"id":2,"title":"book1","updated_at":"2011-06-24T10:11:17Z"}}]

and extension should not be .html but .xml or .json