Uploading v3.1.3.

git-svn-id: https://plugins.svn.wordpress.org/admin-page-framework/trunk@964912 b8457f37-d9ea-0310-8a92-e5e31aec5664
Marked v3.1.3 as stable.

git-svn-id: https://plugins.svn.wordpress.org/admin-page-framework/trunk@964915 b8457f37-d9ea-0310-8a92-e5e31aec5664