OpenStack Storage Service

Mostly a copy&paste from Rackspace Storage:

* Obvious name replacements (s/rackspace/openstack)
* Use OpenStack.authenticate_v2 authentication
* Removed CDN stuff for now, since I'm not sure if that's present in vanilla Swift installs.
* Ported also the tests from Rackspace

All the tests passing, tested against Swift 1.4.8 (Ubuntu Precise) and Keystone 2012.2 (Precise again, backports from the Ubuntu Cloud archives)