Update twitter_user.rb

Hi Jordan,

Awesome project! I'm gonna open a PR or two with small changes and a question or two. Don't worry about actually merging them in, I just like the way they create a prompt for discussion. If I ask something you're not already 100% familiar with, that's totally ok as well, just google around and see what you can come up with. We're more excited about people who learn than people who know everything.

First one: How would this change affect the way your app interacts with Twitter's API? What implications might it have for more complicated tasks, such as if you needed to fetch the recent tweets for everyone in a computed follower intersection?