added cookie option to captcha

metager/app/Http/Controllers/HumanVerification.php

metager/app/Http/Kernel.php

metager/app/Models/Verification/CookieVerification.php

metager/app/Models/Verification/HumanVerification.php

metager/lang/de/captcha.php

metager/lang/en/captcha.php

metager/lang/es/captcha.php

metager/resources/less/metager/pages/verify/index.less

metager/resources/views/humanverification/captcha.blade.php