Prep for 4.6.6 release.

git-svn-id: https://plugins.svn.wordpress.org/email-users/trunk@876646 b8457f37-d9ea-0310-8a92-e5e31aec5664
Fixed problem with Groups plugin integration when using non-English languages.

git-svn-id: https://plugins.svn.wordpress.org/email-users/trunk@876647 b8457f37-d9ea-0310-8a92-e5e31aec5664