Changed handler for volume export.

        try:

            job = self.main.job_manager.create(ExportVolume, volume, raddr, rport)

            # we don't run the job in a background thread thus exceptions are

            # sent to the sjRPC

            job.start_current()

            # otherwise we would do

            # job.start()

            # job.join()

            job.start()

            job.wait()

        except Exception:

            logger.exception('Error while exporting volume')

            raise