Merge remote-tracking branch 'upstream/master'

.rspec

BUILD

Gemfile

Makefile

Rakefile

binding.gyp

build.yaml

gRPC.podspec

grpc.gemspec

include/grpc++/client_context.h

include/grpc++/generic/async_generic_service.h

include/grpc++/security/credentials.h

include/grpc++/support/byte_buffer.h

include/grpc++/support/slice.h

include/grpc/grpc.h

package.json

setup.py

src/core/surface/call.c

src/core/surface/validate_metadata.c

src/core/transport/chttp2/bin_encoder.c