multi: Allow interrupt of server startup.

This commit does two things. It starts up the server in a way that
it can be interrupted and shutdown gracefully.
Moreover it makes sure that subsystems clean themselves up when
they fail to start. This makes sure that depending subsytems can
shutdown gracefully as well and the shutdown process is not stuck.

sweep/fee_bumper.go

@@ -701,7 +701,6 @@ func (t *TxPublisher) Stop() error {
 	log.Debug("TxPublisher stopped")
 
 	return nil
-
 }
 
 // monitor is the main loop driven by new blocks. Whevenr a new block arrives,