Routing: When specify in the mapping _routing required, a delete without explicit routing value should automatically be broadcasted to all shards, closes #522.

modules/elasticsearch/src/main/java/org/elasticsearch/action/delete/TransportDeleteAction.java

@@ -97,6 +97,7 @@ public class TransportDeleteAction extends TransportShardReplicationOperationAct
                 if (request.routing() == null) {
                     indexDeleteAction.execute(new IndexDeleteRequest(request), new ActionListener<IndexDeleteResponse>() {
                         @Override public void onResponse(IndexDeleteResponse indexDeleteResponse) {
+                            // TODO what do we do with specific failed shards?
                             listener.onResponse(new DeleteResponse(request.index(), request.type(), request.id()));
                         }