Versioning (#116)

Add versioning check

cli/cmd/fetch.go

@@ -2,6 +2,7 @@ package cmd
 
 import (
 	"github.com/spf13/cobra"
+	"github.com/up9inc/mizu/cli/mizu"
 )
 
 type MizuFetchOptions struct {
@@ -17,6 +18,11 @@ var fetchCmd = &cobra.Command{
 	Use:   "fetch",
 	Short: "Download recorded traffic to files",
 	RunE: func(cmd *cobra.Command, args []string) error {
+		if isCompatible, err := mizu.CheckVersionCompatibility(mizuFetchOptions.MizuPort); err != nil {
+			return err
+		} else if !isCompatible {
+			return nil
+		}
 		RunMizuFetch(&mizuFetchOptions)
 		return nil
 	},