changed plugin name

git-svn-id: https://plugins.svn.wordpress.org/simpletix-ticketing-event-registration/trunk@992259 b8457f37-d9ea-0310-8a92-e5e31aec5664
increase tag 1.5.1

git-svn-id: https://plugins.svn.wordpress.org/simpletix-ticketing-event-registration/trunk@992260 b8457f37-d9ea-0310-8a92-e5e31aec5664