Package recaptcha provides support for reCaptcha 2.0 user response verification. It allows the use of a custom http.Client, and will fall back to http.DefaultClient if none is supplied.

• Testing: While this package has been tested, proper tests should be written in recaptcha_test.go.
• Optional 'remoteip' parameter. This can be automatically retrieved from the http.request, or if we are behind a proxy, via a header.