The composite channel credentials creation does not change the passed-in
channel creds anymore.

Add empty_stream Python interop test.

Accept --use_tls=true and --use_test_ca=true in python interop tests.

cleanup dockerfiles and scripts for old interop infrastructure

Conflicts:
	.gitignore
	gRPC.podspec

Fix release conflict for release-0_11

Make Node coverage reporting only report on actual Node source files

Restrict number of iterations for UnaryCallPerformance test

Make ruby RpcServer stop waiting for calls when it gets null calls

Revert global_env usage for build_interop_image job

PHP: add remaining auth interop tests

C# ref docs should not be in master branch

Distribute roots.pem with the Node package

Cache encodings accepted by peer on mdelem

Enable cloud_to_prod_auth interop tests on Jenkins.