权限控制  页面权限，按钮权限

动态路由

思路：

  1：后台在登录的时候，后端一般会给token，权限数组
     管理后台的导航菜单，一般两级菜单

  [
    {
      "title": "用户管理"
      "icon": "user",
      "zujian": "",
      "path": "/user",
      "children": [
         {
            "title": "删除用户"
             "icon": "delete",
             "zujian": "",
             "path": "/delete",
             "children":
         },
         {
             "title": "增加用户"
              "icon": "add",
              "zujian": "",
              "path": "/add",
              "children":
         }
      ]
    }
  ]

2: 使用权限数组生成左侧的导航菜单

3：使用权限数组生成路由的配置文件，然后动态的追加到vue-router中，addRouters 让动态路由生效