Since the default behavior is quite sane, support just calling ssl_channel_credentials() without explicitly specifying ssl_channel_credentials(None, None, None).

This changes the pattern ssl_channel_credentials(server_crt, None, None) to ssl_channel_credentials(server_crt)

Signed-off-by: Christian Svensson <blue@cmd.nu>

This reorganizes the Python code, scraps the current testing
infrastructure, and implements a simple test discovery and run script
based on the standard Python unittest library so we can trust that our
tests are running.

Also uses the .proto files for the service/stub definitions.

This is in preparation of moving all tests into a separate package to
enable ease of coverage checking and testing.

Fixes #1762.

It was awkward for the generated code to call an API that offered
both insecure_server and secure_server as well as insecure_stub and
secure_stub. With this change there is just a single server function
and a single stub function and security is decided based on arguments
passed.

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

A top-level "grpc" package is added and RPC Framework
is made public.

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.

It's rather unimpressive at the moment with just
one module.

- Adds a dependency to protobuf-ruby in the gemfile
- Updates math.proto to proto3
- Updates math server and client to use protoc protos
- Updates interop server and client to use protoc protos

Also
- Fixes/Updates the noproto samples

TESTED: math_server and math_client can communicate locally.
	Change on 2015/01/07 by temiola <temiola@google.com>
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=83483448

	Change on 2014/12/01 by nnoble <nnoble@google.com>
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Created by MOE: http://code.google.com/p/moe-java
MOE_MIGRATED_REVID=81111468