Only store an Id if it is non-empty


Conflicts:
	src/main/java/org/apache/ws/security/processor/DerivedKeyTokenProcessor.java
	src/main/java/org/apache/ws/security/processor/EncryptedDataProcessor.java
	src/main/java/org/apache/ws/security/processor/SAMLTokenProcessor.java
	src/main/java/org/apache/ws/security/processor/SignatureConfirmationProcessor.java

git-svn-id: https://svn.apache.org/repos/asf/webservices/wss4j/branches/1_6_x-fixes@1609070 13f79535-47bb-0310-9956-ffa450edef68