[WSS-428] - It should be possible to use the useReqSigCert even when the certificate is not sent in the request
 - Already supported, but tests added

git-svn-id: https://svn.apache.org/repos/asf/webservices/wss4j/branches/1_6_x-fixes@1524105 13f79535-47bb-0310-9956-ffa450edef68