Add Windows Support

close_fds parameter for Popen is not supported in Windows:

http://docs.python.org/2.7/library/subprocess.html#subprocess.Popen
 
    If close_fds is true, all file descriptors except 0, 1 and 2 will be closed before 
    the child process is executed. (Unix only). Or, on Windows, if close_fds is true 
    then no handles will be inherited by the child process. Note that on Windows, you
    cannot set close_fds to true and also redirect the standard handles by setting 
    stdin, stdout or stderr.


With this modification we provide a conditional close_fds parameter and thus we can work with eea.converter (and eea.daviz) in a Windows environment. We have tested adding eea.daviz to a buildout created by the Plone Windows installer (Plone 4.2.1 that ships with python 2.6), and when running the zope instance it breaks unless you provide a close_fds=False parameter.