dialect unspecific dao specs

spec/dao.spec.js

+if(typeof require === 'function') {
+  const buster    = require("buster")
+      , Sequelize = require("../index")
+      , config    = require("./config")
+      , dialects  = ['sqlite', 'mysql', 'postgres']
+}
+
+buster.spec.expose()
+
+dialects.forEach(function(dialect) {
+  describe('DAO@' + dialect, function() {
+    before(function(done) {
+      var self = this
+
+      this.sequelize = new Sequelize(config.database, config.username, config.password, {
+        logging: false
+      })
+
+      this.User = this.sequelize.define('User', {
+        username: { type: Sequelize.STRING },
+        touchedAt: { type: Sequelize.DATE, defaultValue: Sequelize.NOW }
+      })
+
+      self.sequelize
+        .getQueryInterface()
+        .dropAllTables()
+        .success(function() {
+          self.User
+            .sync({ force: true })
+            .success(done)
+            .error(function(err) {
+              console.log(err)
+            })
+        })
+        .error(function(err) { console.log(err) })
+    })
+
+    describe('default values', function() {
+      describe('current date', function() {
+        it('should store a date in touchedAt', function() {
+          var user = this.User.build({ username: 'a user'})
+          expect(user.touchedAt instanceof Date).toBeTrue()
+        })
+
+        it("should store the current date in touchedAt", function() {
+          this.useFakeTimers().tick(5000)
+
+          var user = this.User.build({ username: 'a user'})
+          expect(+user.touchedAt).toBe(5000)
+        })
+      })
+    })
+  })
+})