Use mattermost v5 module (#1192)

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

@@ -0,0 +1,30 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package model
+
+import (
+	"encoding/json"
+	"io"
+)
+
+type Audit struct {
+	Id        string `json:"id"`
+	CreateAt  int64  `json:"create_at"`
+	UserId    string `json:"user_id"`
+	Action    string `json:"action"`
+	ExtraInfo string `json:"extra_info"`
+	IpAddress string `json:"ip_address"`
+	SessionId string `json:"session_id"`
+}
+
+func (o *Audit) ToJson() string {
+	b, _ := json.Marshal(o)
+	return string(b)
+}
+
+func AuditFromJson(data io.Reader) *Audit {
+	var o *Audit
+	json.NewDecoder(data).Decode(&o)
+	return o
+}