title: S3 using boto and SigV4 - missing host parameter
body: <p>when developing i used a S3 bucket in ireland, which worked well. For production i want to use the new "Frankfurt" location of S3, but apparently the new Frankfurt region uses the "SigV4" which breaks my python script.</p>
  
  <p>When adding the following block to ~/.boto, i get the following error:</p>
  
  <p>~/.boto:</p>
  
  <pre><code>[s3]
  use-sigv4 = True
  </code></pre>
  
  <p>Error:</p>
  
  <pre><code>File "/usr/lib/python2.6/site-packages/boto/__init__.py", line 141, in connect_s3
  return S3Connection(aws_access_key_id, aws_secret_access_key, **kwargs)
  File "/usr/lib/python2.6/site-packages/boto/s3/connection.py", line 196, in __init__
  "When using SigV4, you must specify a 'host' parameter."
  boto.s3.connection.HostRequiredError: BotoClientError: When using SigV4, 
  you must specify a 'host' parameter.
  </code></pre>
  
  <p>Can anybody please tell me how to specify the "host" parameter? I couldn't find this parameter in a aws/boto documentation.</p>