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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)

...

if not is_port_open(port, http_path=http_path, expect_success=expect_success):
            raise Exception()
    return retry(check, sleep=sleep_time, retries=retries)
def get_free_tcp_port(blacklist=None):
    blacklist = blacklist or []
    for i in range(10):
        tcp = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        tcp.bind(('', 0))
        addr, port = tcp.getsockname()
        tcp.close()
        if port not in blacklist:
            return port
    raise Exception('Unable to determine free TCP port with blacklist %s' % blacklist)
def sleep_forever():
    while True:
        time.sleep(1)
def get_service_protocol():
    return 'https' if config.USE_SSL else 'http'
def timestamp(time=None, format=TIMESTAMP_FORMAT):
    if not time:
        time = datetime.utcnow()
    if isinstance(time, six.integer_types + (float, )):
        time = datetime.fromtimestamp(time)
    return time.strftime(format)
def timestamp_millis(time=None):
    microsecond_time = timestamp(time=time, format=TIMESTAMP_FORMAT_MICROS)
    
    return microsecond_time[:-4] + microsecond_time[-1]
def retry(function, retries=3, sleep=1, sleep_before=0, **kwargs):