title: MagicalRecord -- A fetch request must have an entity
body: <p>I have what I believe to be the simplest possible start to using Magical Record. I simply set up the stack and do a findAll call -- which I expect to return an empty array since this is a first run of the application. My code is below. For some reason, what I actually get is </p>
  
  <pre><code>executeFetchRequest:error: A fetch request must have an entity.
  </code></pre>
  
  <p>I can't for the life of me figure out why. I don't have versions of my data model, or anything really special. Just an entity and a generated NSMangedObject.. Has anyone seen this before?</p>
  
  <pre><code>- (void)applicationDidFinishLaunching:(NSNotification *)aNotification
  {
      [MagicalRecord setupAutoMigratingCoreDataStack];
  
  //    Task *task = [Task MR_createEntity];
  //    task.title = @"Title";
  
      NSArray *contexts = [Task MR_findAll];
      NSLog(@"Initial load found %lu contexts", contexts.count);
  }
  </code></pre>