Check for an app id before creating app

git-svn-id: https://plugins.svn.wordpress.org/smart-app-banner/trunk@1053437 b8457f37-d9ea-0310-8a92-e5e31aec5664
Update copyright message

git-svn-id: https://plugins.svn.wordpress.org/smart-app-banner/trunk@1053444 b8457f37-d9ea-0310-8a92-e5e31aec5664