Separate formats from location with relocate

[mrocklin]

We have file formats

CSV, JSON, HDF5, ...

and locations

SSH, HFDS, S3, ...

Currently we handle both file conversions and file transfers through convert. This ends up blowing up the graph a bit because we have to manage all pairs of format+location.

I wonder if there is some way to orthogonalize these two ideas and have a separate convert graph for formats and some other system for relocation / file transfers.

I don't have a clear idea of how to do this yet but it seems worth thinking about.