Fixes to NuGet packages + extensions

Fixed TinyIOC & ServiceStack package configs.

https://github.com/XForms/Xamarin-Forms-Labs/issues/283#issuecomment-549
89569

Added some extensions to convert native views to images etc.
Fix to ServiceStack serializer

https://github.com/XForms/Xamarin-Forms-Labs/issues/294

Updated unit test projects. Cleanup on HybridWebView.