Add a CreateQueueWithParams function

This allows you to pass along arbitrary attributes when creating a queue, for example `WaitTimeSeconds` for long polling.  It takes a `map[string]string`, and `CreateQueueWithTimeout` is changed to be implemented in terms of it.

This PR also includes a few changes to the test suite, most notably that the tests are moved into the same package as the code.  This is idiomatic, and makes it possible to run the tests while you are developing the code.  It also moves the test server to a different port to avoid conflicting with services that run as part of OS X Server.