Loving this tool so far! I recently ran into an issue where it seems that performing a Put or a Get operation against my local S3 bucket is collapsing XML-like structures. This in turn causes MD5 digest validation errors.

I have an S3 bucket...
```
aws --endpoint-url=http://localhost:4572 s3api create-bucket --bucket my-bucket
```

I start with a file called **test.xml**:
```
<?xml version="1.0" encoding="UTF-8"?>
<?xml-stylesheet type="text/xsl"?>
<submission>
    <field1>fwefwefewfew</field1>
    <field2>fwefwefwe</field2>
    <field3>fefwefwe</field3>
</submission>
```

I then put this object into S3 using the following command:
```
 aws --endpoint-url=http://localhost:4572 s3api put-object --bucket my-bucket --key data/test1 --body test.xml
```

I'll grab the file back using the following command:
```
aws --endpoint-url=http://localhost:4572 s3api get-object --bucket my-bucket --key data/test1 test-back.xml
```

The file now looks like this:
```
<?xml version="1.0" encoding="UTF-8"?>
<?xml-stylesheet type="text/xsl"?>
<submission><field1>fwefwefewfew</field1><field2>fwefwefwe</field2><field3>fefwefwe</field3></submission>
```

I found this while troubleshooting the following exception stack:
```
com.amazonaws.SdkClientException: Unable to verify integrity of data download.  Client calculated content hash didn't match hash calculated by Amazon S3.  The data may be corrupt.
	at com.amazonaws.services.s3.internal.DigestValidationInputStream.validateMD5Digest(DigestValidationInputStream.java:79)
	at com.amazonaws.services.s3.internal.DigestValidationInputStream.read(DigestValidationInputStream.java:61)
	at com.amazonaws.internal.SdkFilterInputStream.read(SdkFilterInputStream.java:72)
	at java.io.FilterInputStream.read(FilterInputStream.java:107)
	at com.amazonaws.util.IOUtils.toByteArray(IOUtils.java:44)
	at com.amazonaws.util.IOUtils.toString(IOUtils.java:58)
	at com.amazonaws.services.s3.AmazonS3Client.getObjectAsString(AmazonS3Client.java:1485)
```

I was able to work around this bug when I collapsed the XML structure myself prior to adding the file to S3. This is not ideal though.

Any ideas on why this is happening? I am using localstack version 0.8.8, installed with pip.

Thanks for any help!

bucket_name = 'test-bucket-%s' % short_uid()
        object_key = 'data'
        self.s3_client.create_bucket(Bucket=bucket_name)
        body = 'Hello\r\n\r\n\r\n\r\n'
        headers = """
            Authorization: foobar
            Content-Type: audio/mpeg
            X-Amz-Content-Sha256: STREAMING-AWS4-HMAC-SHA256-PAYLOAD
            X-Amz-Date: 20190918T051509Z
            X-Amz-Decoded-Content-Length: %s
        """ % len(body)
        headers = dict([[field.strip() for field in pair.strip().split(':', 1)]
            for pair in headers.strip().split('\n')])
        data = ('d;chunk-signature=af5e6c0a698b0192e9aa5d9083553d4d241d81f69ec62b184d05c509ad5166af\r\n' +
            '%s\r\n0;chunk-signature=f2a50a8c0ad4d212b579c2489c6d122db88d8a0d0b987ea1f3e9d081074a5937\r\n') % body
        
        url = '%s/%s/%s' % (os.environ['TEST_S3_URL'], bucket_name, object_key)
        req = PutRequest(url, to_bytes(data), headers)
        urlopen(req, context=ssl.SSLContext()).read()
        
        downloaded_object = self.s3_client.get_object(Bucket=bucket_name, Key=object_key)
        download_file_object = to_str(downloaded_object['Body'].read())
        self.assertEqual(len(str(download_file_object)), len(body))
        self.assertEqual(str(download_file_object), body)
        
        self._delete_bucket(bucket_name, [object_key])
    def test_s3_put_object_on_presigned_url(self):