better log message for none gateway, also make it debug level

src/main/java/org/elasticsearch/index/gateway/none/NoneIndexShardGateway.java

@@ -65,7 +65,7 @@ public class NoneIndexShardGateway extends AbstractIndexShardComponent implement
         // in the none case, we simply start the shard
         // clean the store, there should be nothing there...
         try {
-            logger.info("deleting shard content");
+            logger.debug("cleaning shard content before creation");
             indexShard.store().deleteContent();
         } catch (IOException e) {
             logger.warn("failed to clean store before starting shard", e);