Changed line 170 from 'item.owner' to 'data.photoset.owner' because that's where the Owner ID is in Flickr's JSON response.
If this line isn't changed, then supersized creates URLs images with 'undefined' as the USER ID.
A previous change (pull request #66) appears to have introduced a bug
for user based photos, while fixing a bug for set based photos. This now
uses data.photoset.owner when data.photoset exists, otherwise, reverts