Upload progress is supported by cherokee, but not FileField

Basically I've implemented file upload progress in the most common way. There are still other mechanisms that *might* work, such as uploading with a Perl wrapper or on nginx (both of these have separate projects to enable this functionality). Basically I don't write/support code for architectures I don't use, so these need to be supported in a project that is maintained by someone that can setup/test on that architecture.