IE9 XDR will abort some requests if you do not attach all event handlers

I'm seeing this in our own app our initial xdr post will abort, setting onprogress event handler fixes this.

See thread on [IE Dev Forum](http://social.msdn.microsoft.com/Forums/ie/en-US/30ef3add-767c-4436-b8a9-f1ca19b4812e/ie9-rtm-xdomainrequest-issued-requests-may-abort-if-all-event-handlers-not-specified).

I refactored out the progress method as upload and download both support progress events.