Merge github.com:grpc/grpc into 44

.gitmodules

BUILD

Makefile

binding.gyp

build.yaml

gRPC.podspec

grpc.gemspec

package.json

src/core/client_config/lb_policies/load_balancer_api.c

src/core/client_config/lb_policies/load_balancer_api.h

src/core/proto/grpc/lb/v0/load_balancer.pb.c

src/core/proto/grpc/lb/v0/load_balancer.pb.h

src/csharp/Grpc.IntegrationTesting/Control.cs

src/csharp/Grpc.IntegrationTesting/QpsWorker.cs

src/csharp/Grpc.IntegrationTesting/RunnerClientServerTest.cs

src/csharp/Grpc.IntegrationTesting/ServerRunners.cs

src/csharp/Grpc.IntegrationTesting/Services.cs

src/csharp/Grpc.IntegrationTesting/ServicesGrpc.cs

src/csharp/Grpc.IntegrationTesting/WorkerServiceImpl.cs

src/proto/grpc/lb/v0/load_balancer.options