Changed DefaultCryptoCoverageChecker to require UsernameTokens to be encrypted by default

git-svn-id: https://svn.apache.org/repos/asf/cxf/trunk@1558765 13f79535-47bb-0310-9956-ffa450edef68
Fixing sign_enc demo. Deleting ut_sign demo.

git-svn-id: https://svn.apache.org/repos/asf/cxf/trunk@1558766 13f79535-47bb-0310-9956-ffa450edef68