Bug fix: make sure tmp uploads are deleted, but then forget about them.
Bug fix: make sure tmp uploads are deleted, but then forget about them.

Previously, they would be deleted on the first request, but then the middleware
would attempt to delete them on all future requests, and fail because they're
already gone.

Now we only check for file uploads in the current context, rather than
storing references to them in the middleware itself.

ufront/ufront-mvc,kevinresol/ufront-mvc,kevinresol/ufront-mvc,ufront/ufront-mvc