Print error instead of returning for seed node err

Returning an error would indicate a complete failure initialising the
Ethereum backend. Instead we should print the message and continue.

eth/backend.go

@@ -245,7 +245,7 @@ func (s *Ethereum) Start(seed bool) error {
 	if seed {
 		logger.Infof("Connect to seed node %v", seedNodeAddress)
 		if err := s.SuggestPeer(seedNodeAddress); err != nil {
-			return err
+			logger.Infoln(err)
 		}
 	}