Total file progress information is inaccurate when uploading files with the HTML 5 version of Uploader

The Uploader currently shows inaccurate or inconsistent information in the total file progress area to the left of the "Add More" button. This is due to the fact that uploads occur concurrently, while there are a number of Flash-era assumptions in the code that files will always be uploaded in a one-by-one manner.

This should be fixed by either ensuring that uploads occur synchronously, or preferably by rewriting the state management code to handle asynchronous, concurrent file uploads.