Progress bar option

After having the progress bar for a few weeks, I've found that I really do want to turn off the progress bar on occasion, usually for small uploads (< 1MB), where the upload would finish before the first AJAX request would even get a chance to complete. Plus this makes testing both implementations a lot easier if it can be turned on or off for two elements within the same form.

Similar to the current implementation, these options are never shown if the server doesn't support upload progress at all.