Updating documentation for more Windows info

Specific changes:
 - Connecting to the cluster
    * split into Windows/Unix subsections
    * added much more detail on how to
      configure PuTTY
 - Mounting cluster discs
    * updated Windows text for more details
      on how to map network drives
 - Preparation
    * Changed relative path to wine config
      script to an absolute path, since it
      wasn't clear where the pbsutils path
      was and I didn't know if it was on the
      PATH
 - TODO (comment in beginning of file)
    * Separated into "TODO" and "DONE"
    * Moved a few items to "DONE"