A teacher can choose whether to allow late assignment submissions

1. Login as a teacher, update an 'Upload a single file' assignment and set a due date in the past. Set 'Prevent late submissions' to No.
2. Login as a student and upload a file.
3. Check that the file is uploaded successfully and a download link is displayed together with the submission date and time in red (indicating that it is late).
4. Login as a teacher and access the 'Upload a single file' assignment.
5. Follow the 'View x submitted assignments' link and click the Grade link for the late submission.
6. Check that the submission date has the number of days late shown in brackets after it.