add a --fallback-folder options to better organize uploads in fossology

We need to implement a more sensibile way to upload new packages to fossology. The rule should be: "if it's really new, upload it into the Goofy folder; if it's just a variant of an already existing upload in Goofy, upload it into Goofy-Incoming-Variants". This in order to avoid to flood the audit team with variants, which may have just one or two patches added from the previous variant. The Audit Team will then be able to schedule the reuser agent on the latest of the variants found into Goofy-Incoming-Variants, and manually move it into Goofy, replacing the original variant where it worked.

fixes issue #75 (closed)