Merge remote-tracking branch 'upstream/master' into backward-compat

BUILD

CMakeLists.txt

Makefile

Rakefile

bazel/generate_cc.bzl

binding.gyp

build.yaml

config.m4

examples/BUILD

examples/cpp/helloworld/BUILD

gRPC-Core.podspec

grpc.gemspec

include/grpc++/impl/codegen/call.h

include/grpc/impl/codegen/grpc_types.h

include/grpc/impl/codegen/port_platform.h

package.json

package.xml

setup.py

src/compiler/cpp_generator.cc

src/compiler/python_generator.cc