Fixed bug - only download zoomable images.
Save album images via Mech object.

Instead of interrogating the HTML response object and using its decoded
content to manually open and write to a file, use WWW::Mechanize's built-in
facilities to save the retrieved URL directly to a file.
Do not store any previously requested pages.

By default, WWW::Mechanize stores copies of the mech object after each
request to keep a history.  We do not make use of this feature, so we do not
want to waste any memory by keeping those backups around.
Print number of images in album after parsing.