Use ssl name override if it's in the channel argument

Avoid unnecessary copies during protobuf serialization and deserialization

Add the Python interop client to gce_setup files

Eliminate the Python "assembly" package

Updated Node package version to 0.5.3

Added timeout for tests that hang

Fix segfault in Node 0.11 and Node 0.12

This completes issue #726. All that cascading activation stuff just
didn't work out as cleanly as I had hoped it would.

README: fix the path to the python requirements.txt file

Refactoring within Python RPC Framework

Add missing GRPC_OVERRIDE, NFC

- avoid string copy due to google::protobuf::message::SerializeToString
- avoid string copy due to google::protobuf::message::ParseFromString
- split large message into 8k slices during protobuf serialization
- correct GrpcBufferReader::BackUp

Testing asan configuration with the latest clang compiler fails due to
the warning `-Winconsistent-missing-override`. This patch fixes it.

strcmp: change all !str[n]cmp to str[n]cmp == 0

Signed-off-by: Ronnie Sahlberg <ronniesahlberg@gmail.com>

Change all !str[n]cmp to be str[n]cmp == 0 consistently across the codebase.

Issue #231

Signed-off-by: Ronnie Sahlberg <ronniesahlberg@gmail.com>

The assembly and face layers were mostly redundant except that the
assembly layer had far-better interfaces and the face layer had more
of a reason to exist. Now they are merged.

C++ Credentials Rework

Secure python interop (plus Python<->Python interop unit tests)

Also refactor the interop package to perform client-server interop
testing in a unit test.

This optional value should only be passed in tests.