move test server to port 4455, panic if server can't start

Port 4444 conflicts with another service run by Mac OS X Server on
Mavericks.
move tests into the same package as the code

This makes it possible to run the tests as you develop, especially
if you are developing against a github fork.
add a CreateQueueWithParams function

This allows you to set arbitrary attributes when creating a queue,
like setting WaitTimeSeconds to allow for long-polling.

Reimplement CreateQueueWithTimeout in terms of CreateQueueWithParams
and add unit tests for both functions.
rename to CreateQueueWithAttributes, fix how they're sent

According to the SQS docs, the visibility timeout needs to be provided as
an attribute, and with the name "VisibilityTimeout".
Merge pull request #74 from joeshaw/joeshaw-create-params

Add a CreateQueueWithParams function