refactorize to use xtend

lib/index.js

@@ -1,23 +1,6 @@
 var connectUtils = require('connect').utils,
-    cookie = require('cookie');
-
-var overwrite = function(overwritten) {
-  return (function() {
-    if( arguments.length > 1 ) {
-      for(var objects in arguments ) {
-        overwrite( this, arguments[objects] );
-      }
-    }
-
-    for( var key in arguments[0] ) {
-      if( arguments[0].hasOwnProperty(key) ) {
-        this[key] = arguments[0][key];
-      }
-    }
-
-    return this;
-  }).apply(overwritten, Array.prototype.slice.call(arguments, 1));
-};
+    cookie = require('cookie'),
+    xtend = require('xtend');
 
 function authorize(options) {
   var auth = {
@@ -29,7 +12,7 @@ function authorize(options) {
     fail: null
   };
 
-  overwrite( auth, options );
+  xtend( auth, options );
 
   auth.userProperty = auth.passport._userProperty || 'user';