tagging v2.1.2

git-svn-id: https://plugins.svn.wordpress.org/an-gradebook/trunk@876921 b8457f37-d9ea-0310-8a92-e5e31aec5664
changed stable tag

git-svn-id: https://plugins.svn.wordpress.org/an-gradebook/trunk@876922 b8457f37-d9ea-0310-8a92-e5e31aec5664