listBranches() does not return all branches in a repository

When using `listBranches()` on a repository with _over_ 30 branches, I only get 30 branches in the response. The response includes the page information:

```
link: '; rel="next", ; rel="last"',
```

However, I do not see a way to include options on the [listBranches()](http://github-tools.github.io/github/docs/3.2.3/Repository.html#listBranches) function. Is it currently possible to get back all the branches in the repository?

EDIT: This might be a duplicate of [this feature request](https://github.com/github-tools/github/issues/408).

Start by inspecting the listBranches() entry point and the related feature request in issue #408. Check how the GitHub branches response exposes pagination and how other repository methods accept options. Done means callers can retrieve all branches or control pagination through a documented interface.

索引モデルが issue の本文から書いたものです。