Merge branch 'master' of github.com:grpc/grpc into compression_coverage_2

BUILD

Makefile

binding.gyp

build.yaml

gRPC.podspec

include/grpc++/impl/rpc_service_method.h

include/grpc/support/cmdline.h

src/core/census/grpc_filter.c

src/core/httpcli/httpcli.c

src/core/httpcli/httpcli.h

src/core/iomgr/tcp_server_posix.c

src/core/iomgr/tcp_windows.c

src/core/security/credentials.h

src/core/security/credentials_posix.c

src/core/security/credentials_win32.c

src/core/security/google_default_credentials.c

src/core/security/json_token.c

src/core/support/cmdline.c

src/core/support/string.c

src/core/support/string.h