ISPN-4696 SuspectException kills operation on ClusterRegistryImpl

* Added retry for ClusterRegistry operations

https://issues.jboss.org/browse/ISPN-4696

Note this is only a stop gap solution for the time being since we do not know yet how we want to fully handle nodes leaving during a commit.  At least with the ClusterRegistry we know we can easily retry the command.
I have fixed an issue in CommandAwareRpcDispatcher which was allowing the JGroups SuspectedException to be propagated up erroneously.  I still need to look into more detail, but this Jira should be better off now.