title: Modify db parameter group in AWS RDS using boto
body: <p>Trying to modify a database parameter group on AWS RDS with boto, I hit upon the error below:</p>
  
  <pre><code>from boto import rds
  conn = rds.connect_to_region('eu-west-1', aws_access_key_id=AWS_ACCESS_KEY_ID,     aws_secret_access_key=AWS_SECRET_ACCESS_KEY)
  pg = conn.get_all_dbparameters('mygroup')
  pg.add_param('slow_query_log', True, 'immediate')
  
  
  TypeError
  "unknown type (&lt;type 'str'&gt;)"
   File: /usr/local/lib/python2.6/dist-packages/boto/rds/parametergroup.py, Line: 175
  </code></pre>
  
  <p>Any help would be appreciated</p>