Merge branch 'master' of github.com:grpc/grpc into cpp_docs

BUILD

Makefile

build.json

gRPC.podspec

include/grpc++/client_context.h

include/grpc++/impl/call.h

include/grpc++/server_context.h

include/grpc++/support/string_ref.h

include/grpc/grpc.h

include/grpc/grpc_security.h

include/grpc/support/time.h

src/core/channel/http_client_filter.c

src/core/client_config/resolver_factory.c

src/core/client_config/resolver_factory.h

src/core/client_config/resolver_registry.c

src/core/client_config/resolver_registry.h

src/core/client_config/resolvers/dns_resolver.c

src/core/client_config/resolvers/sockaddr_resolver.c

src/core/client_config/resolvers/zookeeper_resolver.c

src/core/profiling/basic_timers.c