Fix snakeviz on Win32

Note that the 4fe3712 commit cause the following for me on Ubuntu 12.10 which get fixed by doing `sudo pip install -u distribute`. I'm not sure if it's an issue.

      Running setup.py egg_info for package snakeviz
        The required version of distribute (>=0.6.28) is not available,
        and can't be installed while this script is running. Please
        install a more recent version first, using
        'easy_install -U distribute'.
        
        (Currently using distribute 0.6.28dev-r0 (/usr/lib/python2.7/dist-packages))
        Complete output from command python setup.py egg_info:
        The required version of distribute (>=0.6.28) is not available,

    and can't be installed while this script is running. Please

    install a more recent version first, using

    'easy_install -U distribute'.