Git Trees API without path parameter!

## Git Trees

```
param:
    owner
    repo
    sha(ref)

GET /repos/:owner/:repo/git/trees/:sha

```

The API only get root dir. but the sub directory can not get tree list. Here is github api:

```
param:
    owner
    repo
    ref
    path

https://api.github.com/repos/${owner}/${repo}/git/trees/${ref}${path.replace(/^\//, ':')}
```
**it can not get a sub-tree.** 