Turned on 'captcha'

For the one or two of you who have commented anonymously, I wanted to let you know I have turned on the Google 'captcha' app.  It's quite simple to use.  Authors don't have to.  I have had a bit of nuisance spamming in the comments and maybe this will take care of them.  I am reluctant to require a login.

In any case, as I said, it only affects a couple of people.  I would love it if it affected more :-)