Cleanup Metrics upload monitoring: Change main app to be the upload listener.

As part of the quickie hookup for metrics upload, the metrics was the
upload listener, and because of the transient state of the metrics, it
also had a timer to check if uploading. This is ugly. Make it listener-based only (no Timer), and set the MainApp to be the listener of the uploads (which will pass on the info to metrics view if it is alive).