Improved the session affinity code to handle session updates

git-svn-id: https://svn.wso2.org/repos/wso2/carbon/platform/trunk@178968 a5903396-d722-0410-b921-86c7d4935375
added HazelcastGroupManagementAgent

git-svn-id: https://svn.wso2.org/repos/wso2/carbon/platform/trunk@178969 a5903396-d722-0410-b921-86c7d4935375