modify tasks name, add schedule tasks in settings.
add draw_code in utils.py. change views_cgi.py interface get_code_img.
add zip_code in tasks.py, add ZipCode class in utils.py.
modify settings, add debug-toolbar, add more TEMPLATE_CONTEXT_PROCESSORS, modify template files, change /static/ to {{ STATIC_URL }}.
code zip download finished. ZipCode improve.