callback = function () {
                recaptcha = $window.grecaptcha;

                deferred.resolve(recaptcha);
            }
Sets the reCaptcha configuration values which will be used by default is not specified in a specific directive instance.

@since 2.5.0
@param onLoadFunctionName  string name which overrides the name of the onload function. Should match what is in the recaptcha script querystring onload value.