Use mattermost v5 module (#1192)

vendor/github.com/mattermost/mattermost-server/v5/model/mfa_secret.go

@@ -0,0 +1,25 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package model
+
+import (
+	"encoding/json"
+	"io"
+)
+
+type MfaSecret struct {
+	Secret string `json:"secret"`
+	QRCode string `json:"qr_code"`
+}
+
+func (me *MfaSecret) ToJson() string {
+	b, _ := json.Marshal(me)
+	return string(b)
+}
+
+func MfaSecretFromJson(data io.Reader) *MfaSecret {
+	var me *MfaSecret
+	json.NewDecoder(data).Decode(&me)
+	return me
+}