[Sprint/InterestingIguana](bug) Progress bar prematurely finishes on upload end, not on request end. #1500

The issue with comments at the comment is that the XHR progress event returns 100% when the image is uploaded - this is not the end of the network request though, as there is additional server side processing done. The rationale behind doing it this way, is that the progress bar, to the average user, simply means "How long until I can hit post" - they do not care about whether the image is uploaded or not.

In addition I added if (e.lengthComputable) { which should catch some future errors.