ISPN-4222 Add support for distributed entry iterator

* Added distribute entry retriever
* Added local entry retriever (used by repl, local and inval)

https://issues.jboss.org/browse/ISPN-4222
required for https://issues.jboss.org/browse/ISPN-4068

The big pieces are the DistributedEntryRetriever and LocalEntryRetriever.  To test this I would recommend running the DistributedEntryRetrieverStressTest and tweak the values if desired.