Propagate operation results through node.js txnWrapper example

Modifies the callback behavior of the node.js transaction wrapper
code to propogate up all arguments to the callback in the user
defined operation.

Current implementation would only propogate the errors up, and not
any data that the user wishes to have returned.

_includes/app/txn-sample.js

@@ -37,14 +37,15 @@ function txnWrapper(client, op, next) {
         if (err) {
           return handleError(err);
         }
+        var opResults = arguments;
 
         // If we reach this point, release and commit.
         client.query('RELEASE SAVEPOINT cockroach_restart', function (err) {
           if (err) {
             return handleError(err);
           }
           released = true;
-          return done();
+          return done.apply(null, opResults);
         });
       });
     },
@@ -57,7 +58,14 @@ function txnWrapper(client, op, next) {
           next(err);
         });
       } else {
-        client.query('COMMIT', next);
+        var txnResults = arguments;
+        client.query('COMMIT', function(err) {
+          if (err) {
+            return next(err);
+          } else {
+            return next.apply(null, txnResults);
+          }
+        });
       }
     });
   });