Add (or reset) a few metaData properties as respective fields (if they are
available), so that they can be accurately used within the search index.
'lastModifed' is indexed to support query by date, 'contentLength' obtains content length from the HTTP
header, 'type' field is indexed to support query by type and finally the 'title' field is an attempt
to reset the title if a content-disposition hint exists. The logic is that such a presence is indicative
that the content provider wants the filename therein to be used as the title.
Still need to make content-length searchable!