oss上传参数
#### 简要描述：
-oss直传参数信息接口
#### 请求URL:
-GET /_common/oss
#### 返回示例:
```
{
"code": 0,
"msg": "成功",
"data": {
"access_key_id": "LTAI4G4zqoQyAmQv4JY4SfHV",
"directory": "uploads/",
"expire": 6000,
"host": "http://digag.oss-cn-chengdu.aliyuncs.com",
"policy": "eyJleHBpcmF0aW9uIjoiMjAyMC0wOC0xNlQxODozOTo0MFoiLCJjb25kaXRpb25zIjpbWyJzdGFydHMtd2l0aCIsIiRrZXkiLCJ1cGxvYWRzLyJdXX0=",
"signature": "K19t8PL8ERc4poikoiXKVU4Q7ZY="
}
}
```