Reduce the amount of historical data collected.

It takes a long time during deployment and it's not needed.
Collect most recent data first
Split Sunday morning collection into groups

Avoids hitting Quotas when everything starts at once.
Merge pull request #4 from alphagov/split-collection-schedule

Split Sunday morning collection into groups
Merge pull request #3 from alphagov/reverse-collection-order

Collect most recent data first
Merge pull request #2 from alphagov/reduce-collect-init

Reduce the amount of historical data collected.