The form POST operation to S3 accepts a `success_action_status` field which can be set to 200/201/204, see [here](https://docs.aws.amazon.com/AmazonS3/latest/API/RESTObjectPOST.html). Localstack currently handles the `success_action_redirect` field [here](https://github.com/localstack/localstack/blob/master/localstack/services/s3/s3_listener.py#L518) and so we should look into handling the `success_action_status` field too.

The 201 from AWS responds with an XML document with some fields about the object that has just been created in AWS, see below.

```
<PostResponse>
    <Location>https://s3.amazonaws.com/link-to-the-file</Location>
    <Bucket>s3-bucket</Bucket>
    <Key>development/8614bd40-691b-4668-9241-3b342c6cf429/image.jpg</Key>
    <ETag>"32-bit-tag"</ETag>
</PostResponse>
```
if headers.get('x-amz-content-sha256') == 'STREAMING-AWS4-HMAC-SHA256-PAYLOAD':
            modified_data = strip_chunk_signatures(modified_data or data)
            headers['content-length'] = headers.get('x-amz-decoded-content-length')
        
        
        if method == 'POST':
            original_data = modified_data or data
            expanded_data = multipart_content.expand_multipart_filename(original_data, headers)
            if expanded_data is not original_data:
                modified_data = expanded_data
        
        
        if method == 'PUT' and not headers.get('content-type'):
            headers['content-type'] = 'binary/octet-stream'
        
        persistence.record('s3', method, path, data, headers)
        
        query = parsed_path.query
        path = parsed_path.path
        bucket = path.split('/')[1]
        query_map = urlparse.parse_qs(query, keep_blank_values=True)
        
        append_metadata_headers(method, query_map, headers)
        if query == 'notification' or 'notification' in query_map:
            
            response = handle_notification_request(bucket, method, data)
            return response
        if query == 'cors' or 'cors' in query_map: