when I try to upload a large file, localstack basically freezes (and eventually times out).  
But if the file is all `1` bytes it succeeds.

succeeds:
```bash
aws s3 --endpoint-url=http://localhost:4572 mb s3://testbucket
python -c "print '\x01'*10000000" > testfile
echo $(ls -ahl | grep testfile)
aws s3 --endpoint-url=http://localhost:4572 cp testfile s3://testbucket/testfile
```

fails:
```bash
aws s3 --endpoint-url=http://localhost:4572 mb s3://testbucket
python -c "print 'a'*10000000" > testfile
echo $(ls -ahl | grep testfile)
aws s3 --endpoint-url=http://localhost:4572 cp testfile s3://testbucket/testfile
```
so, for me, both the file content and its size determine if this triggers or not. 
I'm using the latest version `0.9.5`
queue_url, queue_attributes = self._create_test_queue()
        self._create_test_notification_bucket(queue_attributes)
        
        file_size = 75000000
        large_file = self.generate_large_file(file_size)
        download_file = new_tmp_file()
        try:
            self.s3_client.upload_file(Bucket=TEST_BUCKET_WITH_NOTIFICATION,
                                       Key=large_file.name, Filename=large_file.name)
            self.assertEqual(self._get_test_queue_message_count(queue_url), '1')
            
            messages = self.sqs_client.receive_message(QueueUrl=queue_url, AttributeNames=['All'])
            message = json.loads(messages['Messages'][0]['Body'])
            self.assertEqual(message['Records'][0]['eventName'], 'ObjectCreated:CompleteMultipartUpload')
            
            self.s3_client.download_file(Bucket=TEST_BUCKET_WITH_NOTIFICATION,
                                         Key=large_file.name, Filename=download_file)
            self.assertEqual(os.path.getsize(download_file), file_size)
            
            self.sqs_client.delete_queue(QueueUrl=queue_url)
            self._delete_bucket(TEST_BUCKET_WITH_NOTIFICATION, large_file.name)
        finally:
            
            large_file.close()
            rm_rf(large_file.name)
            rm_rf(download_file)
    def test_s3_multipart_upload_with_small_single_part(self):