'Update the about item with the new data blob. If data is None,
then delete the about item.'

@classmethod
def update_about_item(cls, course, about_key, data, user_id, store=None):

    temploc = course.id.make_usage_key('about', about_key)
    store = (store or modulestore())
    if (data is None):
        try:
            store.delete_item(temploc, user_id)
        except ValueError:
            pass
    else:
        try:
            about_item = store.get_item(temploc)
        except ItemNotFoundError:
            about_item = store.create_xblock(course.runtime, course.id, 'about', about_key)
        about_item.data = data
        store.update_item(about_item, user_id, allow_not_found=True)
