Shutl::Resource::Rest should ignore any namespacing when inferring resource name

For discussion. It seemed weird to me that including `Shutl::Resource::Rest` in a namespaced module would result in a 404 when trying to access the api, as the namespacing would be included in the inferred `.remote_collection_url`. Eg:

``` ruby
class Shutl::QuoteCollection
  include Shutl::Resource::Rest
end
```

... would look for the resource at /shutl/quote_collections, which won't work. Now, obviously you can use `.collection_url` etc to fix this behaviour, but I think it should ignore namespacing by default - otherwise it may seem like we're requiring users to keep their classes in the global top-level namespace.