Merge github.com:grpc/grpc into error

BUILD

Makefile

build.yaml

examples/python/helloworld/helloworld_pb2.py

examples/python/route_guide/route_guide_pb2.py

gRPC.podspec

grpc.gemspec

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

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

include/grpc/byte_buffer_reader.h

include/grpc/impl/codegen/byte_buffer_reader.h

include/grpc/impl/codegen/grpc_types.h

package.xml

src/compiler/python_generator.cc

src/core/lib/channel/channel_args.h

src/cpp/common/core_codegen.cc

src/cpp/common/core_codegen.h

src/csharp/Grpc.Core.Tests/ClientServerTest.cs

src/csharp/Grpc.Core.Tests/Grpc.Core.Tests.csproj

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