title: Boto DynamoDB not supporting dictionaries?
body: <p>I have the following Python code that tries to store an item into DynamoDB. While everything works fine for strings, etc.. it fails when I try to add a dictionary.</p>
  
  <p>The table has one primary hash-key called "Parameter"</p>
  
  <pre><code>import boto
  from boto.dynamodb import connect_to_region
  
  conn = connect_to_region('eu-west-1')
  
  table = conn.get_table('my-table')
  
  item_dict = {
      'Parameter': 'dbparams',
      'Value': {
          'host': 'myserver',
          'user': 'myusername',
          'password': 'mypass',
          'port': '5555',
      },
  }
  
  item = table.new_item(attrs=item_dict)
  item.put()
  </code></pre>
  
  <p>This results in the following error:</p>
  
  <pre><code>boto.dynamodb.exceptions.DynamoDBValidationError: DynamoDBValidationError: 400 Bad Request
  {'__type': 'com.amazon.coral.validate#ValidationException', 'message': 'Supplied AttributeValue is empty, must contain exactly one of the supported datatypes'}
  </code></pre>
  
  <p>What is the correct way to do this? I couldn't find an example in the Boto docs either.                                                  </p>