normalize submission timestamps
Merge branch 'develop' into feature/normalize-timestamps
Fix metadata tests to handle timestamp sanitization

The file metadata tests were finding the most recent submission by sorting the
submissions in th source directory. Of course, normalizing the timestamps
breaks this. This sorting only needed, however, because the submission POST
unnecessarily included a message along with the file. Removing this allows us
to use the sole submission.

Also removes some unnecessary code.
Merge pull request #335 from garrettr/feature/normalize-timestamps

Feature/normalize timestamps