fixed bugs

git-svn-id: https://plugins.svn.wordpress.org/captcha-bank/trunk@779223 b8457f37-d9ea-0310-8a92-e5e31aec5664
minor change

git-svn-id: https://plugins.svn.wordpress.org/captcha-bank/trunk@779224 b8457f37-d9ea-0310-8a92-e5e31aec5664