Internet calling and messaging service Viber does a solid job of constantly bringing new features to its apps, regardless of the platform. Now, some seven months after iOS 7 was released, Viber is finally changing the looks of its iPhone app to match that flat, minimalist appearance of Apples OS. Aside from overhauling the UI, the Viber application now also lets you create a list of numbers youd like to block and send longer video messages to people.