six is necessary for making these scripts cross compatible
between python 2.x and 3.x

Changes:
Add six to python_deps.include
Include python_deps.include to all Dockerfile templates in test directory
Include python_deps.include to all Dockerfile templates in stress_test directory
Include python_deps.include to all Dockerfile templates in interop_test directory
Replace print statements with print function calls (from futute..)
Replace .iteritems() with .items() wherever necessary
use six.moves to import BaseHTTPServer
Generate new dockerfiles using generate_projects.sh

Remove gmock protobuf dependency from cmake build

Remove unused file

PHP: update composer.json 

PHP: remove gpr_log debug

fixes #7259

Added timeout to port server

Split incoming initial and trailing metadata in Ruby calls

Make handlers optional at server construction

Fix Python interop unit-tests on Windows

Fix _Rendezvous.exception for successful calls

Support composition of arbitrarily many CallCredentials objects

Split Node health check code into a separate package and make it use static codegen

Reduce default max message size

Updated example codegen to use grpcio-tools

Now reasonable defaults are auto-detected by platform (and by specific
Python implementation).

The modified link command was originally taken from a Python 2.x distutils.

Migrated python performance tests to use GA API

using 'using'. Removed unnecessary grpc::string. fixed indentation.

Modified objc plugin to add two types of import statements for well
known protos.
Deleted unnecessary empty.proto as we'll be using wellknown empty.proto
Modified test to use the well known empty.proto.

Removed cython client-side call tracking

Stress tests: Fix metrics-client logging

Make PHP work correctly when receiving a compressed message

PHP: add warning about shutdown function

Change the return status codes according to the doc