LP#1296937: Call _items functions with ids_only parameter

So that we don't do full lookups of titles when we only care about
counts.

Signed-off-by: Thomas Berezansky <tsbere@mvlc.org>
Signed-off-by: Galen Charlton <gmc@esilibrary.com>
LP#1296937: (follow-up) $ids_only is now the last parameter for ->charged_items

Signed-off-by: Galen Charlton <gmc@esilibrary.com>