This class tests the ReplicationTrackerZKImpl class and ReplicationListener interface. One
MiniZKCluster is used throughout the entire class. The cluster is initialized with the creation
of the rsZNode. All other znode creation/initialization is handled by the replication state
interfaces (i.e. ReplicationPeers, etc.). Each test case in this class should ensure that the
MiniZKCluster is cleaned and returned to it's initial state (i.e. nothing but the rsZNode).