Fixing WS-SC Cancel operation + added unit tests


Conflicts:
	systests/ws-security/src/test/java/org/apache/cxf/systest/ws/wssc/WSSCUnitTest.java
	systests/ws-security/src/test/resources/org/apache/cxf/systest/ws/wssc/DoubleItWSSC.wsdl
	systests/ws-security/src/test/resources/org/apache/cxf/systest/ws/wssc/unit-server.xml

git-svn-id: https://svn.apache.org/repos/asf/cxf/branches/2.7.x-fixes@1537479 13f79535-47bb-0310-9956-ffa450edef68