Merge remote-tracking branch 'upstream/master'

.gitignore

INSTALL

Makefile

build.json

examples/tips/client.cc

examples/tips/client.h

examples/tips/client_main.cc

examples/tips/client_test.cc

examples/tips/empty.proto

examples/tips/label.proto

examples/tips/pubsub.proto

src/php/ext/grpc/credentials.c

src/python/__init__.py

src/python/_framework/__init__.py

src/python/_framework/foundation/__init__.py

src/python/_framework/foundation/_logging_pool_test.py

src/python/_framework/foundation/logging_pool.py

test/cpp/interop/client.cc

tools/run_tests/build_python.sh

tools/run_tests/run_python.sh