Add back freshTimestamp

Author: jenssegers

src/Jenssegers/Mongodb/Model.php

@@ -199,6 +199,16 @@ protected function getDateFormat()
         return $this->dateFormat ?: 'Y-m-d H:i:s';
     }
 
+    /**
+    * Get a fresh timestamp for the model.
+    *
+    * @return MongoDate
+    */
+    public function freshTimestamp()
+    {
+        return new MongoDate;
+    }
+
     /**
      * Get the table associated with the model.
      *