Added Javascript for external use

git-svn-id: https://plugins.svn.wordpress.org/pesapal-pay/trunk@818694 b8457f37-d9ea-0310-8a92-e5e31aec5664
Tagging version 1.2.3

git-svn-id: https://plugins.svn.wordpress.org/pesapal-pay/trunk@818695 b8457f37-d9ea-0310-8a92-e5e31aec5664