* Switched to System.Text.Json for .NET Standard 2.0 target. Added caching of ZipkinEndpoints. Added support for sending RemoteEndpoint to Zipkin API.
* Code review feedback.
* Code review.
* Zipkin performance improvements.
* Made json header static.
* Removed debug code.
* Bumped up the numbers of spans in benchmark to get more consistent results.
* Code review.
Co-authored-by: Sergey Kanzhelev <S.Kanzhelev@live.com>
Mikel Blanchard