Api方式创建selector和rule返回500错误码

[sydowma]

orange版本：0.8.0

接口请求：

curl http://xx.xx.xx.xx:7777/divide/selectors -X POST -H "Authorization:xxxx" -d '"selector":
{
"name": "add-by-api",
"type": 0,
"judge": {},
"handle": {
"continue": true,
"log": false
},
"enable": true
}'

// 后续 更改了请求体，参照 dashboard 的请求，必须添加一个 key 为 selector 才可以，例如

selector=%7B%22name%22%3A%22test1%22%2C%22type%22%3A0%2C%22judge%22%3A%7B%7D%2C%22handle%22%3A%7B%22continue%22%3Atrue%2C%22log%22%3Afalse%7D%2C%22enable%22%3Afalse%7D

也就是说，现有的键值对为 value ，再添加一个 selector 作为 key

[sydowma]

@shuaijinchao @wujunze