If the uploaded file is a NIST file, the upload function will split it
and extract the images. Those images will later on be stored in the DB
like the other uploaded images.
If the uploaded file is not a NIST file, the normal process will be
done.

The original entire filename is still encrypted on the client-side. Only
the extension is passed to the backend to allow a particular processing
for NIST files. The file extension should not contain any sensitive
information regarding the donor of the fingerprint data.

Rename the path variable to subpath to separate it from the path
flask variable instruction

This reverts commit dbe2ba20.

By adding the baseurl variable to the location of the cdn, the files for
each icnml version (production, developement, ...) will use the correct
set of cdn files

Needed to serve the cdn files from the cdn folder

Not mendatory, but done for readability regards