Currently, git-annex takes a very lazy approch to displaying
progress into. It just lets rsync or whatever display the progress
for it, in the terminal.

Something better is needed for the [[webapp]]. There needs to be a
way for the web app to know what the current progress is of all transfers.

To get this info for downloads, git-annex can watch the file as it arrives
and use its size.

TODO: What about uploads? Will i have to parse rsync's progresss output?
Feed it via a named pipe? Ugh. Check into librsync.

This is one of those potentially hidden but time consuming problems.