Merge pull request #2607 from jtattermusch/csharp_improvements

src/csharp/Grpc.Core.Tests/ClientServerTest.cs

src/csharp/Grpc.Core/AsyncDuplexStreamingCall.cs

src/csharp/Grpc.Core/Channel.cs

src/csharp/Grpc.Core/ChannelOptions.cs

src/csharp/Grpc.Core/Grpc.Core.csproj

src/csharp/Grpc.Core/Internal/MetadataArraySafeHandle.cs

src/csharp/Grpc.Core/Internal/ServerCallHandler.cs

src/csharp/Grpc.Core/Metadata.cs

src/csharp/Grpc.Core/Server.cs

src/csharp/Grpc.Core/ServerCallContext.cs

src/csharp/Grpc.Core/Version.cs

src/csharp/Grpc.Core/VersionInfo.cs

src/csharp/Grpc.HealthCheck/Settings.StyleCop

...ationTesting.Client/Grpc.IntegrationTesting.Client.csproj

...ationTesting.Server/Grpc.IntegrationTesting.Server.csproj

src/csharp/Grpc.IntegrationTesting/InteropClient.cs