Count all favs/retweets from the last two months

Before, it would only load the last 200 retweets and 200 favorites, and throw out any past the cutoff date. For people who retweet/favorite a lot, this sucks, cuz it might only count retweets/favorites from the last few days.

This branch changes it to keep requesting retweets/favorites (updating the `max_id` option each time) until the last two months of each have been loaded.