Microsoft today released an update for Microsoft Health app in Windows Phone Store. This updated app v2015.1002.2136.0 now comes with blue themed design instead of purple and support for Band 2. It also includes new features, enhancements and bug fixes. New features added include elevation tracking, UV tracking, sleep cycle related improvements and more.
Update it from Windows Phone Store from the below link. Pre-order Microsoft Band 2 here from Microsoft Store.