Merge branch 'grpclb_resolver_changes' into grpclb_resolver_changes2

BUILD

CMakeLists.txt

Makefile

binding.gyp

build.yaml

config.m4

examples/cpp/helloworld/greeter_async_client.cc

examples/cpp/helloworld/greeter_async_client2.cc

examples/cpp/helloworld/greeter_async_server.cc

gRPC-Core.podspec

grpc.gemspec

include/grpc/impl/codegen/atm.h

include/grpc/impl/codegen/atm_gcc_atomic.h

include/grpc/impl/codegen/atm_gcc_sync.h

include/grpc/impl/codegen/atm_windows.h

package.xml

src/core/ext/client_config/client_channel.c

src/core/ext/client_config/lb_policy_factory.c

src/core/ext/client_config/subchannel.c

src/core/ext/lb_policy/grpclb/grpclb.c