Update readme.txt in prep for 3.9.11 release

git-svn-id: https://plugins.svn.wordpress.org/register-plus-redux/trunk@987427 b8457f37-d9ea-0310-8a92-e5e31aec5664
Bump trunk to 3.9.12

git-svn-id: https://plugins.svn.wordpress.org/register-plus-redux/trunk@987430 b8457f37-d9ea-0310-8a92-e5e31aec5664
Updated Tested To flag

git-svn-id: https://plugins.svn.wordpress.org/register-plus-redux/trunk@987431 b8457f37-d9ea-0310-8a92-e5e31aec5664