[cairo] web updates

[Nis Martensen]

> The cairo wiki is accumulating more spam and we do not notice...

... because web edits with empty commit messages do pollute the
working tree (checkout) and trigger a refresh, but do not get
committed to git. After the wiki has thus accumulated spam,
unsuspecting users doing useful edits then inadvertently commit
the stuff to git.

To check if there is new spam, one has to login to annarchy, cd
into the working tree and run "git diff --cached". Since the changes
are local, they cannot be reverted by a git push from my machine.

Can someone please fix the setup to either accept empty commit
messages (so that we can see the spam) or disallow web editing?

Thanks,
 Nis