Remove manually-entered notes that contained the filenames

Remove the notes that contained the filenames of the files loaded into
Omeka - these note fields were manually entered, when entered.
In the remediated metadata xml file, we searched for <item_-_MODS_-_Notes_*>
elements that contained the string "Original file" and removed these elements.
Remove prepended URL from filename
Change .jpg to .tif in filenames for Ballets Russes