cbc: print size of items

Change-Id: Ic36a409fd9c5cc7d797b4336c611f9c7c9ccae55
Reviewed-on: http://review.couchbase.org/42186
Reviewed-by: Sergey Avseyev <sergey.avseyev@gmail.com>
Tested-by: Mark Nunberg <mnunberg@haskalah.org>