title: Django filter foreign key by booking dates
body: <p>I have the following model:</p>
  
  <pre><code>class House(models.Model): 
     Name = models.CharField(max_length=200, unique=True) 
     Reference = models.CharField(max_length=50, unique=True)
  
  class Booking(models.Model): 
     House = models.ForeignKey(House, related_name='booking')
     InitialDate = models.DateField()
     FinalDate= models.DateField()
  </code></pre>
  
  <p>Now, I want to perform a query to filter all the AVAILABLE houses for a range date (eg: 2013-07-21 to 2013-07-30), so It should exclude all the houses with a booking starting and ending between those two dates.
  I would be able to perform this query with raw SQL but no with the django syntax.</p>
  
  <p>Could anyone please help?</p>
  
  <p>Many thanks!</p>