Merge branch 'security_handshaker1' into security_handshaker2

.gitignore

BUILD

CMakeLists.txt

Makefile

binding.gyp

build.yaml

config.m4

examples/csharp/helloworld-from-cli/Greeter/project.json

...les/csharp/helloworld-from-cli/GreeterClient/project.json

...les/csharp/helloworld-from-cli/GreeterServer/project.json

examples/csharp/helloworld/Greeter/Greeter.csproj

examples/csharp/helloworld/Greeter/packages.config

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

examples/csharp/helloworld/GreeterClient/packages.config

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

examples/csharp/helloworld/GreeterServer/packages.config

examples/csharp/route_guide/RouteGuide/RouteGuide.cs

examples/csharp/route_guide/RouteGuide/RouteGuide.csproj

examples/csharp/route_guide/RouteGuide/packages.config

...harp/route_guide/RouteGuideClient/RouteGuideClient.csproj