further refactoring - adding context to logs, missing comments
improvements as per peer reveiews
incorporating comments from the code review meeting
Take out 'Message counter reset' into a seperate store method
Remove slot associations during purge
Adding javadoc comments
Removing unused properties from MsgData
Remove slots in nodes only if in clustering mode
Merge pull request #166 from hastef88/queue_purge_feature_hector_support

Queue purge further refactoring - adding context to logs, missing comments