Make sure CSS classes for coloring help texts for file size validation
are not just added but also removed appropriately
Make client-side file size validation more helpful by showing max upload size
DRY: Put code that sanitizes the name of the uploaded file in a
separate utility function
Make sure file name is sanitized before it is accessed by any view logic
Increase vertical spacing for imports
No need to pass 'r' flag to ZipFile constructor in
validate_zip_contents: We are not extracting the archive at this point
DRY: Put code that writes the uploaded file to disk in separate
utility function
DRY: Put code that extracts uploaded zip archive in separate utility function
Set up control flow for handling both .zip *and* .xml files
Fix: Pass all required arguments to utils.write_file function
When checking MIME types, don't write files to disk if their extension
is different from '.xml' or '.zip'