Capcha on posting

It would be nice to add capcha on posting feature. I think it a better alternative than Akismet, which is more of remedial measurement.

[FooBarWidget]

Captcha decreases user friendliness though. Most commenting forms don't ask for a captcha. If a captcha feature is added then it must be a configuration option.

[abbr]

I have implemented reCAPTCHA as an option and tested working. See https://github.com/abbr/juvia.