Fix python interpreter version check

[abhinavdas]

The version check for python is broken. This pull request proposes a fix. I am pasting the output from python running on my macbook.

Abhinavs-MacBook-Pro: $ python Python 2.7.10 (default, Jul 30 2016, 18:31:42) [GCC 4.2.1 Compatible Apple LLVM 8.0.0 (clang-800.0.34)] on darwin Type "help", "copyright", "credits" or "license" for more information.

import platform platform.version() 'Darwin Kernel Version 16.0.0: Mon Aug 29 17:56:20 PDT 2016; root:xnu-3789.1.32~3/RELEASE_X86_64' platform.version() >= '3' True import sys sys.version_info.major 2 sys.version_info.major >= 3 False