det.py: returns bad file list in read_dir
rmg_det_to_db: quarantine just the unreadable files
rmg_process: remove empty det directories after importing to db and archiving
rmg_det_to_db: clean up
det.py: fix comments
est.py: fix ResolveIdError call
ResolveIdError: changed it to be more explicit and caught and resolved correctly
rmg_det_to_db: catch when find succedes but returns no directories, or fails
rmg_det_to_db: don't search sites that don't exist in det_files
rmg_det_to_db: added site directory to error message for easier troubleshooting
Merge branch 'master' into tracking