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!
bootstrap_installation()
    from localstack.services import infra
    return infra.start_infra()
def start_infra_in_docker():
    container_name = MAIN_CONTAINER_NAME
    if docker_container_running(container_name):
        raise Exception('LocalStack container named "%s" is already running' % container_name)
    
    plugin_configs = load_plugins()
    
    canonicalize_api_names()
    services = os.environ.get('SERVICES', '')
    entrypoint = os.environ.get('ENTRYPOINT', '')
    cmd = os.environ.get('CMD', '')
    user_flags = config.DOCKER_FLAGS
    image_name = os.environ.get('IMAGE_NAME', constants.DOCKER_IMAGE_NAME)
    service_ports = config.SERVICE_PORTS
    force_noninteractive = os.environ.get('FORCE_NONINTERACTIVE', '')
    
    plugin_run_params = ' '.join([
        entry.get('docker', {}).get('run_flags', '') for entry in plugin_configs])
    
    regex = r'.*-p\s+([0-9]+)(\-([0-9]+))?:([0-9]+)(\-[0-9]+)?.*'
    match = re.match(regex, user_flags)
    start = end = 0
    if match:
        start = int(match.group(1))
        end = int(match.group(3) or match.group(1))
    def is_mapped(start_port, end_port=None):