content resources not removed when assessments, parts and questions in assessment are removed

you need to be watching the record count of table CONTENT_RESOURCE

to reproduce & test, follow these steps.
1. create an assessment with attachment in sections & questions, remove teh whole assessment and check the count in CONTENT_RESOURCE. the no. remains the same before the fix.
2. create a part with questions and attach files to both, then remove the entire part. Please also try moving the question to other parts. take a look at the count and see if it is correct
3. create a question and attach a no. of fiel to it. then remove the question and check the count in CONTENT_RESOURCE

Sending samigo-app/src/java/org/sakaiproject/tool/assessment/ui/bean/author/ItemAuthorBean.java
Sending samigo-app/src/java/org/sakaiproject/tool/assessment/ui/listener/author/ItemModifyListener.java
Sending samigo-app/src/java/org/sakaiproject/tool/assessment/ui/listener/author/RemoveAssessmentListener.java
Sending samigo-app/src/java/org/sakaiproject/tool/assessment/ui/listener/author/RemovePublishedAssessmentListener.java
Sending samigo-app/src/java/org/sakaiproject/tool/assessment/ui/listener/author/StartInsertItemListener.java
Sending samigo-app/src/java/org/sakaiproject/tool/assessment/ui/listener/delivery/BeginDeliveryActionListener.java
Sending samigo-services/src/java/org/sakaiproject/tool/assessment/facade/AssessmentFacadeQueries.java
Sending samigo-services/src/java/org/sakaiproject/tool/assessment/facade/ItemFacadeQueries.java
Sending samigo-services/src/java/org/sakaiproject/tool/assessment/services/assessment/AssessmentService.java
Transmitting file data .........
Committed revision 15682.