Merge branch 'master' of https://github.com/grpc/grpc into ruby_advanced_interop_server_side

.gitignore

.gitmodules

BUILD

WORKSPACE

bazel/BUILD

bazel/cc_grpc_library.bzl

bazel/generate_cc.bzl

bazel/grpc_build_system.bzl

examples/python/helloworld/greeter_client.py

examples/python/helloworld/greeter_server.py

examples/python/helloworld/helloworld_pb2.py

examples/python/helloworld/helloworld_pb2_grpc.py

examples/python/multiplex/helloworld_pb2.py

examples/python/multiplex/helloworld_pb2_grpc.py

examples/python/multiplex/multiplex_client.py

examples/python/multiplex/multiplex_server.py

examples/python/multiplex/route_guide_pb2.py

examples/python/multiplex/route_guide_pb2_grpc.py

examples/python/multiplex/run_codegen.py

examples/python/route_guide/route_guide_client.py