Implementation of reCAPTCHA functionality.

Created two methods: recaptcha_display() and recaptcha_check().  See the
docs for details.
Remove extraneous version string.

Left version string in dist.ini when I told dzil to get it from the
module.  Oops.
Very basic "can-it-load?" testing.
Added a short TODO list.
Don't need the Markdown-based readme, do I?