prepare for move

grpc-common/csharp/Greeter.sln

grpc-common/csharp/Greeter/.gitignore

grpc-common/csharp/Greeter/Greeter.csproj

grpc-common/csharp/Greeter/Helloworld.cs

grpc-common/csharp/Greeter/HelloworldGrpc.cs

grpc-common/csharp/Greeter/Properties/AssemblyInfo.cs

grpc-common/csharp/Greeter/packages.config

grpc-common/csharp/Greeter/protos/helloworld.proto

grpc-common/csharp/GreeterClient/.gitignore

grpc-common/csharp/GreeterClient/GreeterClient.csproj

grpc-common/csharp/GreeterClient/Program.cs

grpc-common/csharp/GreeterClient/Properties/AssemblyInfo.cs

grpc-common/csharp/GreeterClient/packages.config

grpc-common/csharp/GreeterServer/.gitignore

grpc-common/csharp/GreeterServer/GreeterServer.csproj

grpc-common/csharp/GreeterServer/Program.cs

grpc-common/csharp/GreeterServer/Properties/AssemblyInfo.cs

grpc-common/csharp/GreeterServer/packages.config

grpc-common/csharp/README.md

grpc-common/csharp/route_guide/.gitignore