# Process XForms postings. We know that we have XForms in the
      # following cases:
      # method eq 'POST' && content-type eq 'application/xml'
      # method eq 'POST' && content-type =~ /multipart\/related.+start=/
      # There are more cases, actually, but for now, we don't support other
      # methods for XForm posts.
      # In a XForm POST, the QUERY_STRING is parsed normally.
      # If the content-type is 'application/xml', we just set the param
      # XForms:Model (referring to the xml syntax) param containing the
      # unparsed XML data.
      # In the case of multipart/related we set XForms:Model as above, but
      # the other parts are available as uploads with the Content-ID as the
      # the key.
      # See the URL below for XForms specs on this issue.
      # http://www.w3.org/TR/2006/REC-xforms-20060314/slice11.html#submit-options