Uploading v3.1.5.

git-svn-id: https://plugins.svn.wordpress.org/admin-page-framework/trunk@975932 b8457f37-d9ea-0310-8a92-e5e31aec5664
Marked 3.1.5 as stable.

git-svn-id: https://plugins.svn.wordpress.org/admin-page-framework/trunk@975934 b8457f37-d9ea-0310-8a92-e5e31aec5664