title: connect to a DB using psycopg2 without password
body: <p>I have a postgres database on my localhost I can access without a password</p>
  
  <pre><code>$ psql -d mwt
  psql (8.4.12)
  Type "help" for help.
  
  mwt=# SELECT * from vatid;
    id   | requester_vatid |...
    -----+-----------------|...   
    1719 | IT00766780266   |...
  </code></pre>
  
  <p>I want to access that database from django. So I put in <code>DATABASES</code></p>
  
  <pre><code>DATABASES = {
      'default': {
          'ENGINE': 'django.db.backends.postgresql_psycopg2',
          'NAME': 'mwt',
          'USER': 'shaoran',
          'HOST': 'localhost'
      }
  }
  </code></pre>
  
  <p>Since I don't need a password to access my test database I didn't provide any <code>PASSWORD</code> value in the settings.</p>
  
  <pre><code>$ ./manage.py shell
  &gt;&gt;&gt; from polls.models import Vatid
  &gt;&gt;&gt; Vatid.objects.all()
    connection_factory=connection_factory, async=async)
    OperationalError: fe_sendauth: no password supplied
  </code></pre>
  
  <p>I tried using <code>PASSWORD: ''</code> but I get the same error message. I tried to use <code>PASSWORD: None</code> but that didn't help either.</p>
  
  <p>I've been searching the django documentation about this but I cannot find anything useful. It is possible to configure <code>django.db.backends.postgresql_psycopg2</code> to accept empty password?</p>