Improve copy display in search results

Improve copy display in search results

Even though we were trying to root our findnodes() call at a specific
point in the DOM, the XPath was retrieving all volume elements in the
entire DOM and we were therefore getting duplicate items listed in the
search results. Accordingly, use the volume ID to root the search to the
specific volume.

Also, offer designers a bit more of an opportunity to style the holdings
by placing them in a table as well. Bonus points for using thead/th, eh?

Signed-off-by: Dan Scott <dan@coffeecode.net>