[TOS] Need TOS wiki spam prevention!

[Sebastian Dziallas]

So I'm going to keep this short, since I'm at the SoftHum workshop
right now. Attendees were confused as to why the
teachingopensource.org wiki was broken. As it turns out, it wasn't.
Rather, two spammers had entirely obfuscated the main page.

It is (1) obvious that there's spam happening and (2) clear that it's
significantly preventing people from contributing.

Can we please put measures into place preventing this?

I'm not particularly interested in a conversation whether captchas are
useful or not. As long as *something* does the job and prevents *some*
bots from spamming us, that's already better than what we have right
now.

Thanks a lot to Chris for responding immediately in IRC and locking
the front page!

-s