Plugin management page: now properly sorted by name.

git-svn-id: http://yourls.googlecode.com/svn@833 12232710-3e20-11de-b438-597f59cd7555
Make 'official' outgoing links use yourls.org

git-svn-id: http://yourls.googlecode.com/svn@834 12232710-3e20-11de-b438-597f59cd7555
PluginList: clearer description

git-svn-id: http://yourls.googlecode.com/svn@835 12232710-3e20-11de-b438-597f59cd7555