This PR adds a whitelist of safe files to download with
`Content-Disposition: inline;` from the backend, all other files will be
force download via `Content-Disposition: attachment;` existing svg files
will still be rendered in a secure way via the html `image` tag.
reference: https://digi.ninja/blog/svg_xss.php
Signed-off-by: Lenin Alevski <alevsk.8772@gmail.com>