Investigate whether we need checksum tracking for copied DTS files

[briehl]

The MVP for the DTS file mover just uses shutil.move to move files from the DTS staging directory to the user's directory. For more security and data integrity, we might want to do the following:

1. make a list of all files to move
2. copy files one at a time, running checksum checks (md5 would probably be enough)
3. if all checksums are ok, remove all files from dts staging dir
4. if not, log errors, decide how to communicate what failed (maybe drop a "dts_file_errors.log" file in their directory or something)