Hello all,

I have noticed that when I generate a presigned url for a file that will be uploaded to S3 that the Lambda function does not get triggered. It seems to only be happening for presigned url. I was able to successful have it trigger when I use the command line and upload a file through `aws s3 cp`. 

To recreate:
1: have any lambda function be added to an s3 bucket. My lambda configurations look as followed:
```
aws s3api --endpoint-url=http://localstack:4572 create-bucket --bucket mybucket;
aws s3api --endpoint-url=http://localstack:4572 create-bucket --bucket code;
aws s3 cp --endpoint-url=http://localstack:4572 --acl public-read /resources/example.zip s3://code/;
aws lambda create-function --endpoint-url=http://localstack:4574 --function-name MyLambdaFunction--runtime 'nodejs8.10' --handler 'index.handler' --role 'anyRole' --code S3Bucket=code,S3Key=example.zip,S3ObjectVersion=1.0.0;
```
Then add this lambda configuration to the bucket
```
{
    "LambdaFunctionConfigurations": [
        {
            "LambdaFunctionArn": "arn:aws:lambda:us-east-1:000000000000:function:MyLambdaFunction",
            "Events": [
                "s3:ObjectCreated:*"
            ]
        }
    ]
}
```
by running
```
aws s3api --endpoint-url=http://localstack:4572 put-bucket-notification-configuration --bucket 'mybucket' --notification-configuration file:///resources/notification.json;
```
2: Generate a presigned url for the bucket you added the lambda too

```
aws s3 presign --endpoint-url=http://localstack:4572 s3://mybucket/test.txt  --expires-in 300
```
3:
```
 curl --upload-file test.txt -v http://localstack:4572/mybucket/test.txt?AWSAccess
KeyId=dummyaccess&Expires=1571680684&Signature=TbCFh1rzkNYwNEooaQKcJPF4%2Fss%3D
```

Lambda does not seem to get triggered.

Any help or fixes?

Thank you so much for your time and help. Localstack has been a great tool!
if 's3.amazonaws.com' not in headers.get('host', ''):
            headers['host'] = 'localhost'
        
        if 'Content-MD5' in headers and not self.is_s3_copy_request(headers, path):
            response = check_content_md5(data, headers)
            if response is not None:
                return response
        modified_data = None
        
        to_find = to_bytes('<LocationConstraint>us-east-1</LocationConstraint>')
        if data and data.startswith(to_bytes('<')) and to_find in data:
            modified_data = data.replace(to_find, to_bytes(''))
        
        
        
        
        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