The processing of nascent uploads.
- Documentation on general design
- want to log all possible errors to the end-user
- changes file holds all uploaded files in a tree
- changes.files and changes.dsc
- DSC represents a source upload, and creates sources
- but DSC holds DSCUploadedFiles, weirdly
- binary represents a binary upload, and creates binaries
- source files only exist for verify() purposes
- NascentUpload is a motor that creates the changes file, does
verifications, gets overrides, triggers creation or rejection and
prepares the email message