Pull a random sampling, format SQL better
Pull out OriginalDownloder

Try various remote paths as per Wendy's instructions. In case files are
found at other paths, update OriginalFilePath with the new value.
Fixup requires
Ignore 404s in OriginalDownloader
Update exporter to expect SupportingFilePath key
Fix Downloader logic

* Modify alternate paths logic
* Break after first successful potential path is found
* Remove local file on 404 errors
* Output what was downloaded
* Update specs
Modify export query

* Separately output Original and Supporting files based on ReadLevel
* Use LEFT JOINs to get records regardless of attached files
* Take most recent (judging from ID) with non-null subjects