API Pagination

The GitHub API list responses are paginated. We had an issue where the documentation repo was on page 2, and was never seen by Okydoky. This is a quick fix, but ideally we should have an iterator abstraction for repos. We actually solved this for events in another project:

`GitHub` is a `requests.session` wrapper. We’re also getting good mileage out of URLObject from @zacharyvoase. Comments?

```python
def org_events(page="1"):
    """Yield organization events for a user. """

    with GitHub() as github:
        url = (
            api_url
            .relative(
                '/users/{}/events/orgs/{}'
                .format(session['user']['login'], github_org))
            .add_query_params(dict(page=page))
        )
        response = github.get(url)

    response.raise_for_status()

    for event in response.json:
        yield event

    links = parse_link_header(response.headers.get('Link'))
    if 'next' in links:
        next = URL(links['next']).query.dict['page']
        if next == page:
            raise StopIteration  # Raise exception?
        for event in org_events(page=next):
            yield event

    raise StopIteration
```