list all available roles


git-svn-id: https://plugins.svn.wordpress.org/publishing-stats/trunk@1031827 b8457f37-d9ea-0310-8a92-e5e31aec5664
use a native wp function to get the list of users 


git-svn-id: https://plugins.svn.wordpress.org/publishing-stats/trunk@1031829 b8457f37-d9ea-0310-8a92-e5e31aec5664
release version 0.6


git-svn-id: https://plugins.svn.wordpress.org/publishing-stats/trunk@1031830 b8457f37-d9ea-0310-8a92-e5e31aec5664