Cannot fetch all milestones

I want to fetch all milestones even if the data span multiple pages.
However, currently it fetches only first 30 records.
Then I checked source code and found `listMilestones` method uses `this._request` method ([code](https://github.com/github-tools/github/blob/22b889cd48cd281812b020d85f8ea502af69ddfd/lib/Issue.js#L146))
while other listing methods like `listIssues` use `this._requestAllPages`.
Is this intended?

### Versions

- Node - 6.2.0
- github-api - 3.0.0

Start in lib/Issue.js at the listMilestones method referenced by the issue, then compare its request path with listIssues and the _requestAllPages method. Confirm how milestone pagination is handled and verify that fetching milestones returns records from every page rather than only the first 30.

Rédigé par le modèle d'indexation à partir du texte de l'issue.