[Feature Request] Ability to fetch a single page of items in a list

Would be nice to be able to fetch only a page of repositories, repo commits, and other lists instead of fetching the entire thing every time. Currently they call into _requestAllPages which automatically fetches everything from github, which can take awhile for long lists.

@mtscout6 suggested on gitter that a generator function would be a good way to accomplish this.

If there's a good direction to go in, I can probably work on this.