* Return correct error code when fetching a queue that does not exist
* Improve SQS Queue get and set attributes
* Queue creation and set_attributes uses the same code path
- ensure bool/int values are cast correctly
* RedrivePolicy is handled properly with set_attributes
- _setup_dlq is called
- is json decoded, so that returned RedrivePolicy is not json
encoded twice
* As per AWS not all attributes are returned when they are not set, for
example RedrivePolicy, FifoQueue, Policy, Kms*
* WaitTimeSeconds is not a queue attribute switch to
ReceiveMessageWaitTimeSeconds