Merge pull request #3207 from jtattermusch/csharp_update_examples

examples/csharp/Greeter/Helloworld.cs

examples/csharp/Greeter/HelloworldGrpc.cs

examples/csharp/Greeter/protos/helloworld.proto

examples/csharp/GreeterClient/Program.cs

examples/csharp/helloworld/.nuget/packages.config

examples/csharp/helloworld/Greeter.sln

examples/csharp/helloworld/Greeter/.gitignore

examples/csharp/helloworld/Greeter/Greeter.csproj

examples/csharp/helloworld/Greeter/Helloworld.cs

examples/csharp/helloworld/Greeter/HelloworldGrpc.cs

...ples/csharp/helloworld/Greeter/Properties/AssemblyInfo.cs

examples/csharp/helloworld/Greeter/packages.config

examples/csharp/helloworld/GreeterClient/.gitignore

...ples/csharp/helloworld/GreeterClient/GreeterClient.csproj

examples/csharp/helloworld/GreeterClient/Program.cs

...sharp/helloworld/GreeterClient/Properties/AssemblyInfo.cs

examples/csharp/helloworld/GreeterClient/packages.config

examples/csharp/helloworld/GreeterServer/.gitignore

...ples/csharp/helloworld/GreeterServer/GreeterServer.csproj

examples/csharp/helloworld/GreeterServer/Program.cs