Merge github.com:grpc/grpc into buffer_pools_for_realsies

BUILD

CMakeLists.txt

Makefile

binding.gyp

build.yaml

config.m4

doc/interop-test-descriptions.md

...es/node/dynamic_codegen/route_guide/route_guide_client.js

...les/node/static_codegen/route_guide/route_guide_client.js

gRPC-Core.podspec

grpc.gemspec

package.xml

src/core/ext/client_channel/README.md

src/core/ext/client_channel/channel_connectivity.c

src/core/ext/client_channel/client_channel.c

src/core/ext/client_channel/client_channel.h

src/core/ext/client_channel/client_channel_factory.c

src/core/ext/client_channel/client_channel_factory.h

src/core/ext/client_channel/client_channel_plugin.c

src/core/ext/client_channel/connector.c