Merge branch 'master' into untypedAPI

include/grpc/support/slice_buffer.h

src/core/support/slice_buffer.c

src/cpp/proto/proto_utils.cc

src/python/src/grpc/_adapter/fore.py

src/python/src/grpc/_adapter/rear.py

src/python/src/grpc/early_adopter/_reexport.py

src/python/src/grpc/early_adopter/implementations.py

src/python/src/grpc/framework/assembly/__init__.py

src/python/src/grpc/framework/assembly/implementations.py

...ython/src/grpc/framework/assembly/implementations_test.py

src/python/src/grpc/framework/assembly/interfaces.py

src/python/src/grpc/framework/face/implementations.py

src/python/src/setup.py

test/core/support/slice_buffer_test.c

tools/gce_setup/grpc_docker.sh

tools/gce_setup/interop_test_runner.sh

tools/run_tests/python_tests.json