categoryinfo is only availlable for categories, pep8 changes

categoryinfo is now a Category attribute. Assinging it from a page
object raises an AttributeError as suggested in the comment. There
is no need to try calling the site method. It always return a dict.

Change-Id: I0b73f4f07dbb079a42345290ebf6c259a23442b9
Merge "categoryinfo is only availlable for categories, pep8 changes"