Restore 'get-item-uuid-by-name to working state

Bring it up to date with changes in the SPARQL API.
Fix half the functions in tags.lisp

Tags now known to be working:
- list-all-tags
- get-tag-by-name
- store-tag

Tags remaining to be fixed:
- delete-tag-by-name
- add-tag-to-item
- get-tagnames-for-item

Move the latter three to the bottom of the file, with notes indicating
that they're not currently working.