Revert "devilry.apps.student: Removed."

This reverts commit 86cca7f8caa3c3f5827d4c5114d8650fbc1778ca.
devilry.apps.student: Removed all except the views.
devilry.apps.student: Removed.
devilry_student: Added the old delivery file download views.

Fixes #617.
Add a redirect view that handles the old "new feedback" and "delivery receipt" URLs.

Fixes #616.