Merge github.com:grpc/grpc into large_async_secure_and_fixed

include/grpc++/impl/codegen/call.h

src/core/ext/client_config/subchannel.c

src/core/ext/transport/chttp2/transport/chttp2_transport.c

src/core/ext/transport/chttp2/transport/internal.h

src/core/ext/transport/chttp2/transport/parsing.c

src/csharp/Grpc.Core.Tests/Internal/AsyncCallTest.cs

src/csharp/Grpc.Core/Internal/AsyncCall.cs

src/node/tools/bin/protoc.js

src/node/tools/bin/protoc_plugin.js

src/python/grpcio/tests/stress/__init__.py

src/python/grpcio/tests/stress/client.py

src/python/grpcio/tests/stress/metrics_server.py

src/python/grpcio/tests/stress/test_runner.py

src/ruby/ext/grpc/extconf.rb

src/ruby/tools/README.md

src/ruby/tools/bin/protoc.rb

src/ruby/tools/bin/protoc_grpc_ruby_plugin.rb

src/ruby/tools/grpc-tools.gemspec

src/ruby/tools/os_check.rb

src/ruby/tools/version.rb