Revert custom nivo slider changes

git-svn-id: https://plugins.svn.wordpress.org/ml-slider/trunk@817425 b8457f37-d9ea-0310-8a92-e5e31aec5664
Add 'Add slider' button to posts and pages

git-svn-id: https://plugins.svn.wordpress.org/ml-slider/trunk@817426 b8457f37-d9ea-0310-8a92-e5e31aec5664