ACCUMULO-802 added namespace locking to the rest of the tableOps and put them in a consistent order (namespace then table), switched to using HdfsZooInstance to get the instance for the namespaceId
ACCUMULO-802 changed error type given to thrift for TableNamespaceNotFoundExceptions so they don't cause a RuntimException when caught on the client side
ACCUMULO-802 fixed problems with some TableOps not locking correctly, fixed null pointer from some tables missing their namespace during randomwalk