Merge branch 'master' into lockfree-stack

.gitignore

.travis.yml

BUILD

Makefile

build.json

gRPC.podspec

include/grpc++/auth_context.h

include/grpc++/client_context.h

include/grpc++/server_context.h

include/grpc/grpc.h

include/grpc/grpc_security.h

include/grpc/support/time.h

src/core/channel/census_filter.c

src/core/client_config/subchannel.c

src/core/iomgr/iomgr.c

src/core/iomgr/pollset_multipoller_with_epoll.c

src/core/iomgr/pollset_posix.c

src/core/iomgr/pollset_windows.c

src/core/iomgr/socket_windows.c

src/core/iomgr/tcp_client_posix.c