added upgrade notice

git-svn-id: https://plugins.svn.wordpress.org/scormcloud/trunk@906286 b8457f37-d9ea-0310-8a92-e5e31aec5664
stable version back to 1.1.8

git-svn-id: https://plugins.svn.wordpress.org/scormcloud/trunk@906289 b8457f37-d9ea-0310-8a92-e5e31aec5664