By default, captcha values are triple md5 hashed and stored in cookies, and when the user enters the captcha
value the value is also triple md5 hashed and the two values are then compared.
Sometimes, your users may have a very restrictive cookie policy and so cookies will not be set, and therefore,
they will never be able to get past the CAPTCHA control. If it's the case, call this method and set the storage
method to "session".
In this case, call this method and set the the storage method to "session".