Updates express middleware to support async definitions (#291)

`next` argument is optional and if set it will block until it's called

Readme.md

@@ -91,8 +91,10 @@ var orm = require('orm');
 var app = express();
 
 app.use(orm.express("mysql://username:password@host/database", {
-	define: function (db, models) {
+	define: function (db, models, next) {
 		models.person = db.define("person", { ... });
+
+		return next();
 	}
 }));
 app.listen(80);

lib/Express.js

@@ -10,8 +10,6 @@ module.exports = function (uri, opts) {
 	_pending += 1;
 
 	orm.connect(uri, function (err, db) {
-		_pending -= 1;
-
 		if (err) {
 			if (typeof opts.error === "function") {
 				opts.error(err);
@@ -29,14 +27,21 @@ module.exports = function (uri, opts) {
 		} else {
 			_db = db;
 		}
+
 		if (typeof opts.define === "function") {
+			if (opts.define.length > 2) {
+				return opts.define(db, _models, function () {
+					return checkRequestQueue();
+				});
+			}
+
 			opts.define(db, _models);
 		}
 
 		return checkRequestQueue();
 	});
 
-	return function ORM(req, res, next) {
+	return function ORM_ExpressMiddleware(req, res, next) {
 		if (!req.hasOwnProperty("models")) {
 			req.models = _models;
 			req.db     = _db;
@@ -52,6 +57,8 @@ module.exports = function (uri, opts) {
 };
 
 function checkRequestQueue() {
+	_pending -= 1;
+
 	if (_pending > 0) return;
 	if (_queue.length === 0) return;