fix golint issues in core/stores (#527)

core/stores/clickhouse/clickhouse.go

@@ -8,6 +8,7 @@ import (
 
 const clickHouseDriverName = "clickhouse"
 
+// New returns a clickhouse connection.
 func New(datasource string, opts ...sqlx.SqlOption) sqlx.SqlConn {
 	return sqlx.NewSqlConn(clickHouseDriverName, datasource, opts...)
 }