Reviewed by Maciej Stachowiak.

        Add script to check for minimum python version and install if missing on Tiger
        https://bugs.webkit.org/show_bug.cgi?id=38886

        Per Maciej's request on webkit-dev:
        https://lists.webkit.org/pipermail/webkit-dev/2010-May/012785.html
        provide a script which can automatically install Python on Tiger where
        the system provided version is too old to be of use.

        Note this uses the official Mac Python installer from python.org.
        This installs a copy of Python in /Library/Frameworks/Python.framework.
        It also makes symlinks from /usr/local/bin to the Python.framework/bin.

        I have tested this script on Leopard and it worked fine.  I have not
        tested it on Tiger as I do not have access to a Tiger machine.  In
        either case this should provide a great starting point for someone
        wishing to upgrade their copy of Python on Tiger.

        Future patches can make our scripts depend on a success return from this
        script and then they can either skip tests/sections for which python is
        insufficient, or they can fail themselves.

        * Scripts/ensure-valid-python: Added.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@59538 268f45cc-cd09-0410-ab3c-d52691b4dbfc