Several API calls now require pagination

[reiddraper]

This broke our bors today. The collaborators API call now requires pagination, so only the first 30 users could +1 things. Github unfortunately not yet been kind enough to update the documentation.

[reiddraper]

#30 needs to be reverted, after playing with some repos that have more than 30 pull-requests, I see now that is is paginated too.