Make valgrind a bit more useful

Mac-specific Makefile inclusions and installation instructions

Clarify completion queue laws

Expand init/destroy documentation

change metadata getters to return const&

remove nonexistent stream_context_interface.h from build.json

Not yet fully building due to some gtest anomalies on Mac.

Copyright checker

Adding new tests into docker runs

Grpc ruby rename modules

Changes to support server metadata.

More channel argument documentation.

Rebinding of C++ API to the new C core API

Conflicts:
	src/core/surface/server.c

Fix shutdown semantics.