[wip] OpenStack and Rackspace identity users

Addresses #279 
Ideally it should be, but the [API response](http://docs.rackspace.com/auth/api/v2.0/auth-client-devguide/content/GET_getUserById__v2.0_users__userId__User_Calls.html) returns it as a string for some reason (I haven't tested this). There are things we can do to override this, which I'll add in tomorrow. There are still a bunch of incongruities between API and docs that I need to test and iron out.