made volume slider and buttons more attractive

git-svn-id: https://plugins.svn.wordpress.org/soundy-background-music/trunk@910409 b8457f37-d9ea-0310-8a92-e5e31aec5664
modified readme.txt

git-svn-id: https://plugins.svn.wordpress.org/soundy-background-music/trunk@910410 b8457f37-d9ea-0310-8a92-e5e31aec5664