Should handle checks in a "since" manner instead of daily

While it seemed like running dailytwitter every day via cron would be a simple and easy way to handle daily tweet postings, it's already shown itself to be a possible problem. Basically, we only allow dailytwitter to run once a day, and that timestamp shifts forward ever so slightly each time, so eventually it'll cross the midnight boundry and possibly lose a day of Tweets. Likewise, someone may have a temporary outage, or not run cron often enough, or whatever, and as a result it would be nice to actually cull posts "since a certain date". Twitter also has a "since X id" that you can do, which might even be a better idea. The caveat here that needs to be thought about is that there's a limit to how far back you can pull twitter posts. Is this a problem? Perhaps not. Doing it in a more "since" way will require storing more information in the database, but so be it.