Version 1.3.1 + changelog and version bumps.

git-svn-id: https://plugins.svn.wordpress.org/admin-menu-editor/trunk@821096 b8457f37-d9ea-0310-8a92-e5e31aec5664
Stable tag = 1.3.1

git-svn-id: https://plugins.svn.wordpress.org/admin-menu-editor/trunk@821097 b8457f37-d9ea-0310-8a92-e5e31aec5664