Here's a feature that would've been a lot more useful before this week. Amid recent hours-long airport lines, United is adding security wait times to its app. However, the feature arrives a few days after security lines began returning to normal. Hey, at least it'll be there for the next shutdown.At launch, the feature is only available for United's hub airports. That includes Chicago O'Hare, Denver, Houston, LAX, Newark, San Francisco and Washington Dulles. Passengers traveling through any of t...