added basic performance example which saves and reads items

examples/Performance/app.js

+var Sequelize = require(__dirname + "/../../lib/sequelize/Sequelize").Sequelize,
+    sequelize = new Sequelize("sequelize_test", "root", null, { disableLogging: true })
+
+var Person = sequelize.define('person', { name: Sequelize.STRING })
+
+Sequelize.chainQueries([{drop: sequelize}, {sync: sequelize}], function() {
+  var start   = Date.now(),
+      count   = 10000,
+      queries = []
+  
+  for(var i = 0; i < count; i++) {
+    var p = new Person({name: 'someone'})
+    queries.push({ save: p })
+  }
+  
+  Sequelize.Helper.log("Begin to save " + count + " items!")
+  Sequelize.chainQueries(queries, function() {
+    Sequelize.Helper.log("Saving " + count + " items took: " + (Date.now() - start) + "ms")
+    
+    start   = Date.now()
+    Sequelize.Helper.log("Will now read them from the database:")
+    Person.findAll(function(persons) {
+      Sequelize.Helper.log("Reading " + persons.length + " items took: " + (Date.now() - start) + "ms")
+    })
+  })
+})
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