[Clipart] New spam control measures for wiki

[Bryce Harrington]

I've implemented some new spam measures for the OCAL wiki:

* Only logged in users may edit pages

* Proxies are now blocked.  See
  http://meta.wikimedia.org/wiki/Proxy_blocking

* The 'Bad Behavior' extension has been installed and enabled.

* The 'hidden CSS trick' is now blocked.  This technique has been
  heavily abused in our wiki by wiki spammers.

I am also reverting and deleting a bunch of pages created or abused by
spammers.

Bryce