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# Type of request: This is a ...

[x] bug report
[ ] feature request

# Detailed description

In the `ReceiveMessageResult` of the SQS service, I saw this XML from localstack:

```
...
<MessageAttribute>
     <Name>encoding</Name>
    <Value>
        <DataType>String</DataType>
        <StringValue><![CDATA[gzip]]></StringValue>
    </Value>
</MessageAttribute>
...
```

The `<![CDATA[gzip]]>` is slightly different from AWS, which doesn't wrap the value in a `<!CDATA[[]]>` section. This shouldn't be a problem for XML parsers that accept both plain characters and CDATA sections for this element, but the XML parser I was using did not, which causes an error when running the code against localstack but not when running the code against AWS. There is obviously a bug in the XML parser as well, but I thought that I should at least post this here since it is different than what AWS SQS does.

## Expected behavior

MessageAttribute::Value elements should not be wrapped in `CDATA` sections.

## Actual behavior

MessageAttribute::Value elements all seem to be wrapped in `CDATA` sections.

# Steps to reproduce

Send a message to the SQS service which contains some custom message attributes, then make a ReceiveMessageRequest.

## Command used to start LocalStack

`docker run --env "SERVICES=sqs" localstack/localstack`

## Client code (AWS SDK code snippet, or sequence of "awslocal" commands)

...

"""
    Synchronization decorator as described in
    http://blog.dscpl.com.au/2014/01/the-missing-synchronized-decorator.html.
    """
    def _decorator(wrapped):
        @functools.wraps(wrapped)
        def _wrapper(*args, **kwargs):
            with lock:
                return wrapped(*args, **kwargs)
        return _wrapper
    return _decorator
def is_string(s, include_unicode=True, exclude_binary=False):
    if isinstance(s, six.binary_type) and exclude_binary:
        return False
    if isinstance(s, str):
        return True
    if include_unicode and isinstance(s, six.text_type):
        return True
    return False
def is_string_or_bytes(s):
    return is_string(s) or isinstance(s, six.string_types) or isinstance(s, bytes)
def is_base64(s):
    regex = r'^(?:[A-Za-z0-9+/]{4})*(?:[A-Za-z0-9+/]{2}==|[A-Za-z0-9+/]{3}=)?$'
    return is_string(s) and re.match(regex, s)
def md5(string):
    m = hashlib.md5()
    m.update(to_bytes(string))
    return m.hexdigest()
def select_attributes(object, attributes):