I'm trying to setup an lambda function triggered by S3 events within a localstack docker-compose environment.
I've got the latest localstack image running in one service with S3, Lambda and APIGATEWAY and the second service is using `awslocal` to communicate with the localstack.

I have gotten as far as successfully creating a lambda function but when I attempt to `add-permission` I get a 404 Not Found error.

My command is:
```
awslocal lambda add-permission 
--function-name my-lambda-function 
--action lambda:InvokeFunction 
--statement-id s3 
--principal s3.amazonaws.com 
--source-arn arn:aws:s3:::event-source-bucket
```

This works against AWS so I'm not sure what I need to have setup within localstack to get it working.  Thanks for any insight you may have.
import re
from requests.models import Request
from localstack.constants import TEST_AWS_ACCOUNT_ID, MOTO_ACCOUNT_ID
from localstack.utils.aws import aws_stack
from localstack.utils.common import to_str
from localstack.services.generic_proxy import ProxyListener
class ProxyListenerIAM(ProxyListener):
    def forward_request(self, method, path, data, headers):
        if method == 'POST' and path == '/':
            data = self._reset_account_id(data)
            return Request(data=data, headers=headers, method=method)
        return True
    def return_response(self, method, path, data, headers, response):