#_PAYMENT_URL was no longer replaced correctly

git-svn-id: https://plugins.svn.wordpress.org/events-made-easy/trunk@986745 b8457f37-d9ea-0310-8a92-e5e31aec5664
First Data payment button was not being generated correctly

git-svn-id: https://plugins.svn.wordpress.org/events-made-easy/trunk@986747 b8457f37-d9ea-0310-8a92-e5e31aec5664
release 1.5.3

git-svn-id: https://plugins.svn.wordpress.org/events-made-easy/trunk@986749 b8457f37-d9ea-0310-8a92-e5e31aec5664