title: using uuid and bcrypt with django not generating unique values
body: <p>building a uuid then hashing it with bcrypt ends up generating an object with the same value in auth_secret(uuid4() is not generating a unique value for each new instance) every time one is initialized. Here is the terminal output</p>
  
  <pre><code>&gt;&gt;&gt; from quickstart.models import FarmUserAuthentication
  &gt;&gt;&gt; c = FarmUserAuthentication('as')
  &gt;&gt;&gt; d = FarmUserAuthentication('asdfs')
  &gt;&gt;&gt; c
  &lt;FarmUserAuthentication:  $2a$12$euUMcvhPwPsS7SQgiOVGNeWr792cq.tKONl9bTVjY3nvrxpczPqs6&gt;
  &gt;&gt;&gt; d
  &lt;FarmUserAuthentication:  $2a$12$euUMcvhPwPsS7SQgiOVGNeWr792cq.tKONl9bTVjY3nvrxpczPqs6&gt;
  </code></pre>
  
  <p>here is my code in models.py</p>
  
  <pre><code>class FarmUserAuthentication(models.Model):
      auth_id = models.CharField(primary_key = True, max_length = 10)
      hash = bcrypt.hashpw(str(uuid.UUID4()), bcrypt.gensalt())
      auth_secret = models.CharField(max_length=100, default= hash, editable=False)
  </code></pre>