Adding more symmetric encryption tests

git-svn-id: https://svn.apache.org/repos/asf/santuario/xml-security-java/trunk@1600892 13f79535-47bb-0310-9956-ffa450edef68
Use cipher.getIV() if not-null

git-svn-id: https://svn.apache.org/repos/asf/santuario/xml-security-java/trunk@1600893 13f79535-47bb-0310-9956-ffa450edef68