Attempt to swift to eventlet to gevent

This allow to use geventhttpclient with
a connection pool to speed up get_object.
This later will allow to remove at all
dependency to python-swiftclient.
Use imap_unoredered instead of imap
Full support of client connection through gevent

Avoid dependency to python-swiftclient
Avoid dependency to python-keystoneclient
This patch does not include unittest update
Fix unittests after the change to gevent http client
Fix class names according to change to gevent
Fix Keystone authentication

- Use of urlparse
- Allow empty option in config file
Fix missing option in config example