Remove default region from Rackspace services

I've pulled the trigger and removed the default region from all (regioned) Rackspace services. Attempting to instantiate a service without a `:rackspace_region` or appropriate endpoint parameter now results in a message like:

```
There are multiple endpoints available for cloudFiles. Please specify one of the following regions: :ord, :syd, :dfw, :iad. (RuntimeError)
```

Note that `:rackspace_region` is still a `recognizes` rather than a `requires` so that you can still specify the service endpoint manually and bypass the service catalog interrogation.

Also, while I was going through, I noticed that `Queues` and `Storage` didn't have deprecation messages! What should we do about those?

/cc @elight

Fixes #3091.