title: issues with 'Entity' in google app engine tutorial
body: <p>I have an issue with the GAE tutorial. I just started learning how to use it, and I came to face an issue with '@Entity' when I go to the localhost:8888 page to check the '@Entity' list in there, it shows an empty list.... and I don't understand why... I'm following the tutorial line by line !!!</p>
  
  <pre><code>@Entity
  public class CheckIn {
  
     @Id
     @GeneratedValue(strategy = GenerationType.IDENTITY)
     private Key key;
     private String placeId;
     private String userEmail;
     private Date checkinDate;
  </code></pre>