Notebook storage to an OpenStack Swift cluster

This is just a shell so you can see what I'm up to. My goal is to make this work on anyone's deployment of OpenStack Swift ([CERN has a swift cluster, for example](http://www.theregister.co.uk/2013/07/01/rackspace_cern_openstack_partnership/)) as well as Rackspace's CloudFiles (which is OpenStack Swift underneath).  I'm largely following the model of the Azure notebook manager and the guidance in the superclass, `NotebookManager`.

Let me know what you think. I probably don't need to say this, but don't merge it yet!