Asynchronous file uploads

This release fixes problems in the upload feature (in the file tab) on some multi server environments.

In addition, the new implementation uploads files asynchronously. This means the user can choose to hide the upload dialog once the upload starts. The user can then continue to work while the upload continues.

The user can also wait until the dialog pop-down when the upload completes (this used to be the only option), but the rest of the UI is not available during the wait.