Short-term To-Do for 4.1
------------------------

- Add migration+code to add blog_id to category and tags
- fix sparklines controller
- Revert cache filter order
- Push some filter tests into plugins
- url command attack fix
- audit admin, only POST can change state
- verify front page query count (should be 4 queries)

X Add migration to ditch trailing slash from canonical_server_url
X Add migration to ditch *_html
X goals 4.1
X finish edit/delete_url
X delete links helpers, replace with model methods