merge with upstream and resolve conflicts

.travis.yml

BUILD

Makefile

build.json

gRPC.podspec

include/grpc++/async_unary_call.h

include/grpc++/byte_buffer.h

include/grpc++/client_context.h

include/grpc++/completion_queue.h

include/grpc++/config.h

include/grpc++/config_protobuf.h

include/grpc++/impl/call.h

include/grpc++/impl/client_unary_call.h

include/grpc++/impl/proto_utils.h

include/grpc++/impl/rpc_service_method.h

include/grpc++/impl/serialization_traits.h

include/grpc++/impl/service_type.h

include/grpc++/server.h

include/grpc++/server_context.h

include/grpc++/stream.h