With Rackspace, currently (only until July), you can do this:

```ruby
Fog::Compute.new(
  :rackspace_usename => "...",
  :rackspace_api_key => "...",
  :version => "v2",
)
```

... and it will assume a default region under the hood.  However, this is causing some problems for us and so we're removing it in July.

But this is about more than just Rackspace and HP. 

Other OpenStack providers may use OSC. We need to account for them as well. And, so, accounting for a nil region somehow.

We can force the issue at `OSC::Identity#initialize`, requiring `:openstack_region` as a keyword arg there. And, maybe, that would be best.

What do you think?