Add method for defining what data (cities, years) are part of the cron process.

[bcipolli]

This will make it easier for cities to add themselves to this project, and easier to set up a test system that mirrors the production system.

Assigning to the 1.0 RC, as I think this is helpful for making sure our test systems mirror our deploy system.

[adborden]

If I understand this correctly, I'd like re-phrase this.
My assumption is that right now we already import all the jurisdiction data available and the only thing that needs to happen is to fix how we figure out the years to download. Rather than assuming a fixed list (currently), we should assume the current year, and allow the user to override the year with the --year flag.