Merge github.com:grpc/grpc into bm_channel

.pylintrc

CMakeLists.txt

Makefile

bazel/cc_grpc_library.bzl

bazel/generate_cc.bzl

bazel/grpc_build_system.bzl

build.yaml

requirements.txt

src/core/lib/iomgr/udp_server.c

src/csharp/Grpc.Core.Tests/TestResult.xml

src/python/grpcio/grpc/_channel.py

src/python/grpcio/grpc/beta/_client_adaptations.py

src/python/grpcio/grpc/beta/_server_adaptations.py

src/python/grpcio/grpc/beta/implementations.py

src/python/grpcio/grpc/framework/interfaces/base/base.py

src/python/grpcio/grpc/framework/interfaces/face/face.py

templates/tools/dockerfile/apt_get_pyenv.include

tools/dockerfile/push_testing_images.sh

tools/dockerfile/test/python_pyenv_x64/Dockerfile

tools/run_tests/generated/sources_and_headers.json