Merge github.com:grpc/grpc into c++-is-people-too

BUILD

Makefile

binding.gyp

build.yaml

config.m4

gRPC.podspec

grpc.def

grpc.gemspec

package.xml

src/compiler/csharp_generator.cc

src/core/plugin_registry/grpc_cronet_plugin_registry.c

src/csharp/Grpc.Core.Tests/AppDomainUnloadTest.cs

src/csharp/Grpc.Core.Tests/ChannelTest.cs

src/csharp/Grpc.Core.Tests/Grpc.Core.Tests.csproj

src/csharp/Grpc.Core.Tests/GrpcEnvironmentTest.cs

...Grpc.Core.Tests/Internal/CompletionQueueSafeHandleTest.cs

src/csharp/Grpc.Core.Tests/MockServiceHelper.cs

src/csharp/Grpc.Core.Tests/PInvokeTest.cs

src/csharp/Grpc.Core.Tests/ServerTest.cs

src/csharp/Grpc.Core.Tests/ShutdownHookClientTest.cs