Fix goimports issue

Paulo Janotti · Paulo Janotti · commit b7b4ffe9aa6b · 2019-07-31T12:22:43.000-07:00
diff --git a/exporter/zipkinexporter/factory.go b/exporter/zipkinexporter/factory.go
@@ -16,6 +16,7 @@ package zipkinexporter
 
 import (
 	"errors"
+
 	"go.uber.org/zap"
 
 	"github.com/open-telemetry/opentelemetry-service/config/configerror"
