[X] bug report
[ ] feature request

# Detailed description

The AWS API supports Authorization parameters as GET parameters, e.g. here's a GET request to SendMessage on SQS:

```
curl 'http://localhost:4566/000000000000/SomeQueue.fifo?Action=SendMessage&MessageGroupId=Default&MessageDeduplicationId=1615597859837&MessageBody=%7B%22gateway_id%22%3A%20%2204e73c80-3539-499c-92a4-a0b106c2f6ab%22%7D&X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=test%2F20210313%2Fus-east-1%2Fsqs%2Faws4_request&X-Amz-Date=20210313T011059Z&X-Amz-Expires=86400000&X-Amz-SignedHeaders=host&X-Amz-Signature=2c652c7bc9a3b75579db3d987d1e6dd056f0ac776c1e1d4ec91e2ce84e5ad3ae'
```

## Expected behavior

Should send the message and return receipt information.

## Actual behavior

Returns...

```
<?xml version="1.0" encoding="UTF-8"?>
<Error>
    <Code>NoSuchBucket</Code>
    <Message>The specified bucket does not exist</Message>
    <BucketName>000000000000</BucketName>
    <RequestID>7a62c49f-347e-4fc4-9331-6e8eEXAMPLE</RequestID>
</Error>
```

""" Dummy class that can be used for mocking custom attributes. """
    pass
class CustomEncoder(json.JSONEncoder):
    """ Helper class to convert JSON documents with datetime, decimals, or bytes. """
    def default(self, o):
        import yaml  
        if isinstance(o, decimal.Decimal):
            if o % 1 > 0:
                return float(o)
            else:
                return int(o)
        if isinstance(o, (datetime, date)):
            return timestamp_millis(o)
        if isinstance(o, yaml.ScalarNode):
            if o.tag == 'tag:yaml.org,2002:int':
                return int(o.value)
            if o.tag == 'tag:yaml.org,2002:float':
                return float(o.value)
            if o.tag == 'tag:yaml.org,2002:bool':
                return bool(o.value)
            return str(o.value)
        try:
            if isinstance(o, six.binary_type):
                return to_str(o)
            return super(CustomEncoder, self).default(o)
        except Exception:
            return None
class ShellCommandThread(FuncThread):