Regularly fetch older reports too

[konklone]

Right now the cronjobs for Sunlight and oversight.io both look every night for anything from the current year. It's probably also worth:

• looking back to the previous year (once a week?)
• looking back to all previous years (once a month?)

This could catch belatedly redacted/released reports, and old reports that get added later, or whose links get fixed, etc.