# folder

## get_root_folder
### params
'username', 'token'
### return
- code=200, root_folder_id
- code=401, error='未登录'

## folder_list
### params
'username', 'token', 'folder_id'
### return
- code=401, error='未登录'
- code=400, error='文件夹不存在'
- code=404, error='没有权限'
- code=200, children=[] (json列表)

## add_folder
### params
'username', 'token', 'father_folder_id', 'folder_name'
### return
- code=401, error='未登录'
- code=400, error='上级文件夹不存在'
- code=404, error='没有权限'
- code=200

## delete_folder
### params
'username', 'token', 'folder_id'
### return
- code=401, error='未登录'
- code=400, error='无此文件夹'
- code=404, error='没有删除文件的权限'
- code=200