Cloud Networking

PR for Rackspace networking. Unfortunately, it looks like none of the Rackspace operations for this service can be delegated to the Openstack Neutron code due to differences in URLs and `Network` objects.

- [x] Networks
 - [X] Operations
 - [X] Unit Tests
 - [x] Acceptance Tests
- [x] Virtual Interfaces
 - [X] Operations
 - [X] Unit Tests
 - [x] Acceptance Tests 
Hmm... The problem is that Neutron support will eventually be supported, so I think we should reserve the `rackspace/networking/v2` import path for that. Plus what we currently have isn't _technically_ its own service, just a subset of the Compute service. So IMHO, we should probably either:

- move the directory structure into `compute/v1/networks` and change the package names
- change the import path to something like `networking/novanetworks`. Nova networks will soon be deprecated by OpenStack I think