Sqsd doesn't forward "MessageAttributes"

[andysmchk]

Hello, I've noticed a bug with receiving X-Aws-Sqsd-Attr- headers, they are just missed.
Looks like "MessageAttributes" were ignored.

Suggestion

Sqsd\Sqsd::collectMessageHeaders() excepts a wrong format of "MessageAttributes", according to the aws-sdk version from composer.json.
Actual format:

"MessageAttributes": {
        "PostalCode": {
          "DataType": "String",
          "StringValue": "ABC123"
        },
        "City": {
          "DataType": "String",
          "StringValue": "Any City"
        }
      }

Line 125 of that class contains redundant foreach construction

foreach ($message['MessageAttributes'] as $messageAttribute) {
    foreach ($messageAttribute as $messageAttributeName => $messageAttributeValues) {

After removing it 'MessageAttributes' are passed as expected.

foreach ($message['MessageAttributes'] as $messageAttributeName => $messageAttributeValues) {

Please let me know if i can help you to resolve this issue.
Thank you.