Merge pull request #2418 from jtattermusch/csharp_healthchecking

src/csharp/Grpc.HealthCheck.Tests/.gitignore

...harp/Grpc.HealthCheck.Tests/Grpc.HealthCheck.Tests.csproj

src/csharp/Grpc.HealthCheck.Tests/HealthClientServerTest.cs

src/csharp/Grpc.HealthCheck.Tests/HealthServiceImplTest.cs

src/csharp/Grpc.HealthCheck.Tests/Properties/AssemblyInfo.cs

src/csharp/Grpc.HealthCheck.Tests/packages.config

src/csharp/Grpc.HealthCheck/.gitignore

src/csharp/Grpc.HealthCheck/Grpc.HealthCheck.csproj

src/csharp/Grpc.HealthCheck/Grpc.HealthCheck.nuspec

src/csharp/Grpc.HealthCheck/Health.cs

src/csharp/Grpc.HealthCheck/HealthGrpc.cs

src/csharp/Grpc.HealthCheck/HealthServiceImpl.cs

src/csharp/Grpc.HealthCheck/Properties/AssemblyInfo.cs

src/csharp/Grpc.HealthCheck/packages.config

src/csharp/Grpc.HealthCheck/proto/health.proto

src/csharp/Grpc.sln

src/csharp/build_packages.bat

src/csharp/generate_proto_csharp.sh