added class level comment
Merge pull request #39 from sajinidesilva/slot_Imp

added class level comment
Incorrectly trying to delete queue and subscription from registry without replacing @ is fixed.
	modified:   components/andes/org.wso2.carbon.andes.authorization/src/main/java/org/wso2/carbon/andes/authorization/andes/QpidAuthorizationHandler.java
Code style related issues fixed
Exception handling improved
Cassandra Server feature and zookeper related code removed
Docs added