Add image counts to metadata

[tfmorris]

There's a spreadsheet with the counts of small, medium, and large images in the 31K editions which have had images posted to Flickr. Since it includes the sysnum, we can use it to extend our metadata.

https://docs.google.com/spreadsheets/d/1f9-xeIvgR8hRJTuJ8ThQJ5FxcvB0JqtNwvpf3C3OF6o/edit?usp=sharing