preparing announcement for 3.4.0 release

git-svn-id: https://svn.apache.org/repos/asf/spamassassin/trunk@1565581 13f79535-47bb-0310-9956-ffa450edef68
promotions validated

git-svn-id: https://svn.apache.org/repos/asf/spamassassin/trunk@1565582 13f79535-47bb-0310-9956-ffa450edef68