Create the mock Queues service.

Mostly by refactoring methods out into a Common module, much like the
Storage service.
Enable Queues service tests for mocking.
Enable Cloud Queues request tests.
Mock the create_queue call.
Mock the list_queues call.
Mock the delete_queue call.
Mock the get_queue call.
No need to map! here, we're modifying the hashes.
Mock the queue_stats request.

It's not actually tracking statistics now; I'll have to fill that in once I get
to the requests that post and claim messages.
Handle a corner case in the create_queue mock.
On to the messages_tests.
Mock the create_message call.
get_message and list_messages mocks.
Initial support for mocking delete_message.

I need to investigate the actual exceptions in those two cases.
Enable claim_tests in mocking mode.
Mock the create_claim request.
create_claim returns a 204 for empty claims.
Mock the get_claim request.

Move claim creation responsibility to the MockQueue, like messages.
Mock the update_claim request.
Mock the delete_claim request.