ENH: Update Python to 2.7.11

Also updates 'msvc9compiler' custom version backporting change from
python/cpython@1a2c95d (Issue 0004214: Remove ineffectual /pdb:none option
from msvc9compiler.py) - See https://bugs.python.org/issue4214

For the rational behind the introduction of a custom version of
msvc9compiler, see r23040 (COMP: Fix python_patched_msvc9compiler.py the
"right" way)

Reviewed-by: Max Smolens <max.smolens@kitware.com>
Suggested-by: Michael Powell <mwpowellhtx@gmail.com>

Associated python-cmake-buildsystem are listed below:

$ git shortlog ed5f9bc..b012e1e --no-merges
Chuck Atkins (3):
Create and use append_if_absent macro for constructing compiler options
Use the POSITION_INDEPENDENT_CODE target property instead of -fPIC
Adjust GCC-specific compiler options to work for Clang, Intel, and PGI

Jean-Christophe Fillion-Robin (6):
Create CONTRIBUTING.md
Add convenience macro "check_cmake_property_exists"
Fix distutils.sysconfig._python_build() on windows
Fix distutils.test_get_python_inc on windows copying headers into build dir
Fix test_get_config_h_filename in test_sysconfig.py
Add support for python 2.7.11rc1

Matt McCormick (4):
Add the ability to specify the Python version in the CMake configuration.
Update remark on supported Python versions.
Add Python 2.7.11 download support.
Make Python 2.7.11 the default.

Simon Su (1):
Expect BZIP2_INCLUDE_DIR when building bz2 module.

git-svn-id: http://svn.slicer.org/Slicer4/trunk@24903 3bd1e089-480b-0410-8dfb-8563597acbee