Merge pull request #3227 from ctiller/yyy

examples/cpp/helloworld/greeter_async_client.cc

examples/cpp/helloworld/greeter_async_server.cc

examples/cpp/helloworld/greeter_client.cc

examples/cpp/helloworld/greeter_server.cc

include/grpc++/channel.h

include/grpc++/client_context.h

include/grpc++/completion_queue.h

include/grpc++/create_channel.h

include/grpc++/grpc++.h

include/grpc++/security/auth_context.h

include/grpc++/security/credentials.h

include/grpc++/security/server_credentials.h

include/grpc++/server.h

include/grpc++/server_builder.h

include/grpc++/support/async_stream.h

include/grpc++/support/byte_buffer.h

include/grpc++/support/channel_arguments.h

include/grpc++/support/slice.h

include/grpc++/support/status.h

include/grpc++/support/status_code_enum.h