Add support for logs format (#38)

Author: andresmgot

query.go

@@ -21,6 +21,8 @@ const (
 	FormatOptionTimeSeries FormatQueryOption = iota
 	// FormatOptionTable formats the query results as a table using "LongToWide"
 	FormatOptionTable
+	// FormatOptionLogs sets the preferred visualization to logs
+	FormatOptionLogs
 )
 
 // Query is the model that represents the query that users submit from the panel / queryeditor.
@@ -149,6 +151,11 @@ func getFrames(rows *sql.Rows, limit int64, converters []sqlutil.Converter, fill
 		return data.Frames{frame}, nil
 	}
 
+	if query.Format == FormatOptionLogs {
+		frame.Meta.PreferredVisualization = data.VisTypeLogs
+		return data.Frames{frame}, nil
+	}
+
 	count, err := frame.RowLen()
 
 	if err != nil {