Transparent, restriction aware staging and public file structures

We need an abstraction for handling all files related to an upload.

There are two different structures for uploads in two different states: staging and public. Possible operations on uploads differ based on this state. Staging is used for processing, heavily editing, creating hashes, etc. Public is supposed to be a almost readonly (beside metadata) storage.

fs/staging/<upload>/metadata/<calc>.json
                    /raw/**
                    /archive/<calc>.hdf5
                    /.frozen
                    /.public
                    /.restricted
fs/public/<upload>/metadata.json.gz
                  /raw-public.bagit.zip
                  /raw-restricted.bagit.zip
                  /archive-public.hdf5.zip
                  /archive-restricted.hdf5.zip

This is an complex issue with multiple sub-tasks

• implementing/testing an respective the uploads.py module
• adopt processing and api accordingly
• make the raw file API restriction aware
• do potential adaptations to the staging GUI

This is a prerequisite for building reasonable mirror functionality. It would allow to move calc (and potentially also user) metadata out of the repository db, which also requires to adopt the repoTool.