Patch objpool.http to support SSL Authentication

Refs #54

The module objpool.http provides pooled connections without SSL
Authentication.
A new connection class is implemented in kamaki.clients.utils.https
The name of the class is HTTPSClientAuthConnection
The PooledHTTPConnection is patched to provide HTTPSClientAuthConnection
instances as https connections.

Also, astakosclient module is patched to use the same https connection class.
Deal with pep8 errors in affected files