resources: Rename Converger to ConvergerUID

This is more correct since we need the Converger method to return the
actual converger!

resources/nspawn.go

@@ -95,7 +95,7 @@ func (obj *NspawnRes) Validate() error {
 
 // Watch for state changes and sends a message to the bus if there is a change
 func (obj *NspawnRes) Watch(processChan chan event.Event) error {
-	cuid := obj.Converger() // get the converger uid used to report status
+	cuid := obj.ConvergerUID() // get the converger uid used to report status
 
 	// this resource depends on systemd ensure that it's running
 	if !systemdUtil.IsRunningSystemd() {