969457: Do not timeout on getting all #rpm_ids

For big repositories `Runcible::Extensions::Repository.rpm_ids` was
time-outing. Fixed by adding pagination to `Repository.rpm_ids`.

The timeout was causing `after_sync` callback failure which led to packages
not being indexed in elasticsearch. Elasticsearch index is used for retrieval
of package count which was wrongly showing 0 without indexed packages.
Merge pull request #68 from pitr-ch/bug/969457-after-sync-timeout

969457: Do not timeout on getting all #rpm_ids