refactored code to easily see mistakes in constant definition

git-svn-id: https://plugins.svn.wordpress.org/ads-campaigns/trunk@893266 b8457f37-d9ea-0310-8a92-e5e31aec5664
updated wordpress version requirements

git-svn-id: https://plugins.svn.wordpress.org/ads-campaigns/trunk@893274 b8457f37-d9ea-0310-8a92-e5e31aec5664