Working on direct uploads to S3.
Remove jQueryFileUpload code. Handle failed uploads.
Create S3File module for URLs and paths.
Add S3 uploader to all forms with uploads.
Update S3File#show for all.
Fix links to grade files.
Add progress bar to all forms.
Only show progress bar during upload.
Update views.
Store full file path and name seperately.
Rake task to migrate to new paths.
Fix challenge files and rake task.
Rewrite rake task. Cleanup.
Fix url scheme and display.
Fix filenames.
Create browsable path.

Upload to S3 with a browsable path that includes the course name, the
assignment name, the upload date, and the file name. The course name has
an id appended to it, as does the assignment name, in order to
distinguish between courses with the name name.
Create browsable paths for all uploads.
Fix loading error.
Fix path stripping.