audio noise level now adjustable

git-svn-id: https://plugins.svn.wordpress.org/confident-captcha/trunk@882023 b8457f37-d9ea-0310-8a92-e5e31aec5664
audio noise level now adjustable, new tag

git-svn-id: https://plugins.svn.wordpress.org/confident-captcha/trunk@882025 b8457f37-d9ea-0310-8a92-e5e31aec5664