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

Add dockerfile template for python_pyenv_x64 docker image
Generate the dockerfile using generate_projects.sh
Modify run_tests.py to include python3.5 and python3.6
Runs python_jessie_x64 for python versions 2.7 and 3.4, and
python_pyenv_x64 for python versions 3.5 and 3.6

A full build of protobuf depends on gmock even though it is not part of
a standrad checkout. This CL explicitly disable the build of the
protobuf tests to get rid of this dependency.

If somebody want to build the protobuf tests then they have to download
gmock to the protobuf directory and specify -Dprotobuf_BUILD_TESTS=ON
to the cmake command line.

Fixes https://github.com/grpc/grpc/issues/7233

Moves all tests into a separate package. This does not change existing
supported means of running tests (e.g. through run_tests.py).

This works around the Cocoapods' linter header_mapping_dir restrictions.
Incidentally, it also removes the need to set build settings in the user
target.

* Add project name and version number
* Fix zlib dependency of grpc
* Include more target (all, protoc, tool groups)

This cmake file only builds the C and C++ code and all the third party
dependencies with very few configuration options but it supports
building on Linux and OSX as well as cross compiling.
(tested {Linux, OSX} -> Android { arm, aarch64, x86 })

Disabling it allows clang-3.4 to run C/C++ on docker

not true