Hotfix file multipart upload vulnerability
Hotfix file multipart upload vulnerability

After raising an error while trying to upload multiple files over
the multipart endpoint, all successful uploaded and temporary saved
files will now be cleaned up from scratch folder in order to prevent
orphans and attacks that could easily fill up the disk.
This is done by extending all raises with the last valid state to be
able to access and delete all successful uploaded files so far.

stuart-thackray/simple_bridge,choptastic/simple_bridge,nitrogen/simple_bridge