registry of already processed directories

[yarikoptic]

we probably want also to be able to be able to

• re-process directory (probably just rerun with --overwrite)
• annotate that a directory X
  • was processed already
  • should not be processed
• given a DBIC dataset with .heudiconv/ report which Accession numbers were already processed (which subject/session)
• for a given study ID, report which accessions were processed (and to where stored) and which weren't, and possibly run a conversion on those which weren't yet (current ad-hoc line to execute is grep -B1 1018_model ~/heudiconv-ls001-20170227.txt | grep DICOM/ | sed -e 's,/001.*,,g' | xargs heudiconv -o ~/test-1018_model)

[yarikoptic]

so the WiP heudiconv_monitor already creates such a database. We should prepopulate it and make use of it also within heudiconv or our specific wrapper around (currently a shell script, bleh, at ~/bin/heudiconv) it to ignore/warning when some directory which was already processed ... we should store it in /inbox/BIDS/.heudiconv/statusdb.json or smth like that.