Return error message when a streaming exception occurs in the soap binding

git-svn-id: https://svn.apache.org/repos/asf/cxf/branches/wss4j2.0-port@1483305 13f79535-47bb-0310-9956-ffa450edef68
Added some StaX SAML system tests

git-svn-id: https://svn.apache.org/repos/asf/cxf/branches/wss4j2.0-port@1483306 13f79535-47bb-0310-9956-ffa450edef68