Two minor tweaks to policy verification code
 a) Allow STR Transform for C14n Algorithm
 b) Allow SupportingToken policies to be "signed" (e.g. when using TLS)

git-svn-id: https://svn.apache.org/repos/asf/webservices/wss4j/trunk@1482406 13f79535-47bb-0310-9956-ffa450edef68