merge with head and resolve conflict

.gitignore

BUILD

Makefile

binding.gyp

build.yaml

doc/grpc-auth-support.md

examples/objective-c/auth_sample/AuthTestService.podspec

examples/objective-c/helloworld/HelloWorld.podspec

examples/objective-c/route_guide/RouteGuide.podspec

gRPC.podspec

include/grpc++/impl/thd_no_cxx11.h

include/grpc++/security/credentials.h

include/grpc/grpc.h

include/grpc/grpc_security.h

include/grpc/support/avl.h

include/grpc/support/slice.h

package.json

reports/interop_html_report.template

src/core/census/grpc_filter.c

src/core/channel/channel_stack.c