Refactor Java upload and download applet into a module
Remove Flash uploader for security reasons

SWFUpload is abandonware with many issues.
Refactor demo mode into a module
Remove unimplemented Amazon asset store
Replace use of tempnam, which is unavailable on App Engine

There is a chance of a collision if files with the same name are uploaded at
the same time to the nearest microsecond. However, sadly, the server already
has other issues that would cause it to error before this could ever be an
issue.
Fix new revision upload to use same mechanism as new item upload
Audit and reformat code for PSR-2 compliance
Fix upload/download controller tests