Added all previous minor releases of gRPC to the matrix.  Modified the testsuite name format for better display test results in sponge.

Added c++ to interop_matrix.  Per earlier conversation, interop_matrix will not run against different compiler/toolchains so we are not addding _<runtime> to c++. This simplifies our setup and reduces unnecesary complexities in the infrastructure.

Created a Java Oracle8 Dockerfile directory and moved all build_interop.sh to under template/.  Added java_oracle8 to the client matrix.

Features included in this merge:
- Added script to build and upload docker image for matrix test.
- Added script to create test cases and created go__master testcases based on it.
- Created dictionary for runtimes and gRPC releases for supported languages.
- Added go 1.7 and 1.8 Dockerfile/templates.

See tools/interop_matrix/README.md for details.

Update run_tests/*.py to use six based isomorphisms and print function
from __future__ module.

Pylint is only enabled for "grpcio/grpc" package,
and various specific checks that currently fail are disabled,
each with a respective TODO item in the .pylintrc file.

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.