Merge github.com:grpc/grpc into optimize_for

.github/ISSUE_TEMPLATE.md

.pylintrc

BUILD

CMakeLists.txt

LICENSE

Makefile

binding.gyp

build.yaml

config.m4

config.w32

doc/PROTOCOL-HTTP2.md

doc/environment_variables.md

gRPC-Core.podspec

grpc.gemspec

include/grpc++/alarm.h

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

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

package.json

package.xml

setup.py