reactor&feat: 重构工单模块 & 支持申请应用工单 (#5352)

* reactor: 修改工单Model，添加工单迁移文件

* reactor: 修改工单Model，添加工单迁移文件

* reactor: 重构工单模块

* reactor: 重构工单模块2

* reactor: 重构工单模块3

* reactor: 重构工单模块4

* reactor: 重构工单模块5

* reactor: 重构工单模块6

* reactor: 重构工单模块7

* reactor: 重构工单模块8

* reactor: 重构工单模块9

* reactor: 重构工单模块10

* reactor: 重构工单模块11

* reactor: 重构工单模块12

* reactor: 重构工单模块13

* reactor: 重构工单模块14

* reactor: 重构工单模块15

* reactor: 重构工单模块16

* reactor: 重构工单模块17

* reactor: 重构工单模块18

* reactor: 重构工单模块19

* reactor: 重构工单模块20

* reactor: 重构工单模块21

* reactor: 重构工单模块22

* reactor: 重构工单模块23

* reactor: 重构工单模块24

* reactor: 重构工单模块25

* reactor: 重构工单模块26

* reactor: 重构工单模块27

* reactor: 重构工单模块28

* reactor: 重构工单模块29

* reactor: 重构工单模块30

* reactor: 重构工单模块31

* reactor: 重构工单模块32

* reactor: 重构工单模块33

* reactor: 重构工单模块34

* reactor: 重构工单模块35

* reactor: 重构工单模块36

* reactor: 重构工单模块37

* reactor: 重构工单模块38

* reactor: 重构工单模块39

apps/tickets/models/comment.py

@@ -0,0 +1,23 @@
+# -*- coding: utf-8 -*-
+#
+from django.db import models
+from django.utils.translation import ugettext_lazy as _
+
+from common.mixins.models import CommonModelMixin
+
+__all__ = ['Comment']
+
+
+class Comment(CommonModelMixin):
+    ticket = models.ForeignKey(
+        'tickets.Ticket', on_delete=models.CASCADE, related_name='comments'
+    )
+    user = models.ForeignKey(
+        'users.User', on_delete=models.SET_NULL, null=True, related_name='comments',
+        verbose_name=_("User")
+    )
+    user_display = models.CharField(max_length=256, verbose_name=_("User display name"))
+    body = models.TextField(verbose_name=_("Body"))
+
+    class Meta:
+        ordering = ('date_created', )