Add delete branch track on pull request comments (#888)

* add delete branch track on pull request comments

* don't change vendor

options/locale/locale_zh-CN.ini

@@ -510,6 +510,7 @@ issues.self_assign_at = `于 %s 指派给自己`
 issues.add_assignee_at = `于 %[2]s 被 <b>%[1]s</b> 指派`
 issues.remove_assignee_at = `于 %s 取消了指派`
 issues.change_title_at = `于 %[3]s 修改标题 <b>%[1]s</b> 为 <b>%[2]s</b>`
+issues.delete_branch_at = `于 %[2]s 删除了分支 <b>%[1]s`
 issues.open_tab=%d 个开启中
 issues.close_tab=%d 个已关闭
 issues.filter_label=标签筛选