verify.captcha: "Please verify the captcha"
invalid.captcha: "Captcha invalid, please try again"
timeout.captcha: "The captcha is no longer valid, please try again"
missinginput.captcha: "Empty secrect key"
invalidinput.captcha: "Invalid secret key"
hostname.captcha: "Hostname mismatch"
badrequest.captcha: "The request could not be completed"