Styling for upgrade to pro media library tabs

git-svn-id: https://plugins.svn.wordpress.org/ml-slider/trunk@887574 b8457f37-d9ea-0310-8a92-e5e31aec5664
More refactorings, add fallback for autoloading classes

git-svn-id: https://plugins.svn.wordpress.org/ml-slider/trunk@887576 b8457f37-d9ea-0310-8a92-e5e31aec5664