remove transaction deprecation notice and check for thenable on return

lib/sequelize.js

@@ -1114,8 +1114,6 @@ module.exports = (function() {
       , ns = Sequelize.cls;
       , ns = Sequelize.cls;
 
 
     if (autoCallback) {
     if (autoCallback) {
-      deprecated('Note: When passing a callback to a transaction a promise chain is expected in return, the transaction will be committed or rejected based on the promise chain returned to the callback.');
-
       var transactionResolver = function (resolve, reject) {
       var transactionResolver = function (resolve, reject) {
         transaction.prepareEnvironment().then(function () {
         transaction.prepareEnvironment().then(function () {
           if (ns) {
           if (ns) {
@@ -1123,7 +1121,7 @@ module.exports = (function() {
           }
           }
 
 
           var result = autoCallback(transaction);
           var result = autoCallback(transaction);
-          if (!result) return reject(new Error('You need to return a promise chain to the sequelize.transaction() callback'));
+          if (!result || !result.then) return reject(new Error('You need to return a promise chain/thenable to the sequelize.transaction() callback'));
 
 
           result.then(function (result) {
           result.then(function (result) {
             return transaction.commit().then(function () {
             return transaction.commit().then(function () {