Ready for 1.3.4 release

git-svn-id: https://plugins.svn.wordpress.org/wp-mailup/trunk@1017502 b8457f37-d9ea-0310-8a92-e5e31aec5664
version number updated in main file wp-mailup

git-svn-id: https://plugins.svn.wordpress.org/wp-mailup/trunk@1017511 b8457f37-d9ea-0310-8a92-e5e31aec5664