Merge enum-ification of Python RPC Framework.

Install PyPI's protobuf into the Python virtual environment.

Add node client and server to the list of interop tests to run

Grpc ruby add a tips client

There may be a way to use third_party's protobuf (and this
may eventually be necessary) but I haven't yet figured out
how to do it correctly. It can happen later.

Fix some TSAN reported errors

Grpc ruby add signet based auth

Initialize mutex

Remove a major source of contention in thread_pool

Prevent a potential deadlock

Build cleaner updates

Fix some memory leaks

Migrate the last of the Python code from Google-internal source control to git.

The source code is moved from src/python to
src/python/src. A setup.py is added at
src/python. The build_python.sh and
run_python.sh scripts are updated to build
and run the Python tests by building a
package and installing it in the developer's
Python 2.7 virtual environment.

And make it easy not to make the same mistake

- notify_one when new work is available to avoid thundering herd
  problems
- checking conditions before entering cv_.wait() prevents a case that
  these are not validated

Fix some typos

Add pprof support to qps client, server

Starts profiling on client and server.
On client, finishes after a test.
On the server, finishes after sigint.

Adding an editorconfig configuration file.

Resolves a deadlock caused by flow control callbacks being made under the lock.

- also fixes the service_account test assertions

- Also fixes some lint issues