First set of changes needed to rewrite entries on the fly

Introduces Command reader for previous version commands
CommandReaderFactory is aware of entry version and returns the appropriate
 command reader. Currently not pooled but should be.
LogEntryConsumer is now aware of entry versions and keeps them
 around if they are of previous versions, so it can translate them.
The DenseNodeTransactionInterceptor now works for adding and removing
 relationships. There is still work to do, but all changes but
 adding/removing properties and labels should work.