'Load all extra non-course content, and calculate metadata inheritance.'

def content_importers(self, system, course_descriptor, course_dir, url_name):

    compute_inherited_metadata(course_descriptor)
    self.load_extra_content(system, course_descriptor, 'course_info', ((self.data_dir / course_dir) / 'info'), course_dir, url_name)
    self.load_extra_content(system, course_descriptor, 'static_tab', ((self.data_dir / course_dir) / 'tabs'), course_dir, url_name)
    self.load_extra_content(system, course_descriptor, 'custom_tag_template', ((self.data_dir / course_dir) / 'custom_tags'), course_dir, url_name)
    self.load_extra_content(system, course_descriptor, 'about', ((self.data_dir / course_dir) / 'about'), course_dir, url_name)
