When creating the following bucket notification configuration:
```json
{
    "QueueConfigurations": [
        {
            "Id": "some-id",
            "QueueArn": "arn:aws:sqs:eu-central-1:123456789:my-queue",
            "Events": [
                "s3:ObjectCreated:*"
            ],
            "Filter": {
                "Key": {
                    "FilterRules": [
                        {
                            "Name": "Prefix",
                            "Value": "path/to/folder/"
                        },
                        {
                            "Name": "Suffix",
                            "Value": ".json"
                        }
                    ]
                }
            }
        }
    ]
}
```
and adding some files to S3, I get the following errors from localstack:

```
localstack.services.s3.s3_listener: Unknown filter name: "Prefix"
localstack.services.s3.s3_listener: Unknown filter name: "Suffix"
```

When I change the FilterRule names from "Prefix" to "prefix" and "Suffix" to "suffix", everything works. AWS supports the capitalised name, so this looks like a bug in localstack.
result += xmltodict.unparse(dest_dict, full_document=False)
        result += '</NotificationConfiguration>'
        response._content = result
    if method == 'PUT':
        parsed = xmltodict.parse(data)
        notif_config = parsed.get('NotificationConfiguration')
        S3_NOTIFICATIONS[bucket] = []
        for dest in NOTIFICATION_DESTINATION_TYPES:
            config = notif_config.get('%sConfiguration' % (dest))
            configs = config if isinstance(config, list) else [config] if config else []
            for config in configs:
                events = config.get('Event')
                if isinstance(events, six.string_types):
                    events = [events]
                event_filter = config.get('Filter', {})
                
                s3_filter = _get_s3_filter(event_filter)
                if s3_filter and not isinstance(s3_filter.get('FilterRule', []), list):
                    s3_filter['FilterRule'] = [s3_filter['FilterRule']]
                
                notification_details = {
                    'Id': config.get('Id'),
                    'Event': events,
                    dest: config.get(dest),
                    'Filter': event_filter
                }
                S3_NOTIFICATIONS[bucket].append(clone(notification_details))
    return response
class ProxyListenerS3(ProxyListener):
    def is_s3_copy_request(self, headers, path):