The async calls in CodePush for ReactWindows can all be executed on any background thread, so adding .ConfigureAwait(false) can improve performance and reduce the likelihood of deadlock. The blocking calls in `InitializeUpdateAfterRestart()` were hanging, but now that .ConfigureAwait(false) is used pervasively, it is no longer a problem.
Fixes#550
Includes the following changes:
* UpdateState.Lastest -> UpdateState.Latest
* Added *Async suffix to Task returning methods
* Using DateTimeOffset in MinimumBackgroundListener
* Disposing IDisposable streams in UpdateManager.DownloadPackage
* Fix hint path for react-native-windows .csproj
* Update project.json to 5.2.2 to match latest ReactWindows project.
* Upgrading Newtonsoft.Json to match latest in ReactWindows.