force xerces version used in webapp

git-svn-id: https://svn.apache.org/repos/asf/archiva/trunk@1565981 13f79535-47bb-0310-9956-ffa450edef68
fix fluentlenium

git-svn-id: https://svn.apache.org/repos/asf/archiva/trunk@1565982 13f79535-47bb-0310-9956-ffa450edef68