Remove notes containing original filenames

Removed the <item_-_MODS_-_Notes_*> that contained "Original filename ...".
The original filename will be retrieved from the <item_-_OriginalFileLoadedIntoOmeka_*>
element, which uses the filename generated by Omeka, instead of using a manually populated
Note field.
Remove the prepending URL paths from the filenames.

To do the above, I used query-replace-regexp, with the following regexp:
http://www.columbia.edu/cu/libraries/inside/working/Russian_Jewish_New_York/Case_0./._../slides/
Change .jpg to .tif in filenames