Need to add support for Github's crappy pagination

[Danack]

   if ($repoTags->pager) {
        $newPages = $repoTags->pager->getAllKnownPages();
        foreach ($newPages as $newPage) {
            $pages[$newPage] = false;
        }
    }

For the record, it's crappy because it's a completely different api call to the original listRepoTags call.