Merge branch 'master' into stream_corked_pr

BUILD

CMakeLists.txt

Makefile

binding.gyp

build.yaml

config.m4

doc/combiner-explainer.md

doc/core/grpc-error.md

doc/http2-interop-test-descriptions.md

examples/node/static_codegen/README.md

gRPC-Core.podspec

grpc.gemspec

include/grpc++/support/channel_arguments.h

include/grpc/impl/codegen/atm.h

package.xml

setup.py

src/compiler/python_generator.cc

src/core/ext/client_channel/channel_connectivity.c

src/core/ext/client_channel/client_channel.c

src/core/ext/client_channel/client_channel_plugin.c