merge with master

.gitmodules

.travis.yml

BUILD

Makefile

README.md

build.json

composer.json

doc/interop-test-descriptions.md

include/grpc++/config.h

include/grpc++/stream.h

include/grpc/grpc.h

include/grpc/grpc_security.h

include/grpc/support/cmdline.h

include/grpc/support/subprocess.h

src/compiler/cpp_generator.cc

src/compiler/csharp_generator.cc

src/compiler/generator_helpers.h

src/compiler/objective_c_generator.cc

src/compiler/objective_c_generator.h

src/compiler/objective_c_generator_helpers.h