added user preview stats result sample
added PreviewStats URI
moved const from struct to static class to avoid instantiation.
Added models and sub models for User/PreviewStats
Users/PreviewStats logic
 /Users/PreviewStats unit tests
Merge branch 'feature/User_Preview_Stats' into develop
CA1405
CA1001 and CA1063 (IDisposable impl.)
Removed unused using, added assembly description and version
Merge branch 'feature/CA_compliance' into develop