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`
self.s3_client.create_bucket(Bucket=TEST_BUCKET_NAME_WITH_POLICY)
        
        policy = {
            'Version': '2012-10-17',
            'Statement': {
                'Action': ['s3:GetObject'],
                'Effect': 'Allow',
                'Resource': 'arn:aws:s3:::bucketName/*',
                'Principal': {
                    'AWS': ['*']
                }
            }
        }
        response = self.s3_client.put_bucket_policy(
            Bucket=TEST_BUCKET_NAME_WITH_POLICY,
            Policy=json.dumps(policy)
        )
        self.assertEqual(response['ResponseMetadata']['HTTPStatusCode'], 204)
        
        saved_policy = self.s3_client.get_bucket_policy(Bucket=TEST_BUCKET_NAME_WITH_POLICY)['Policy']
        self.assertEqual(json.loads(saved_policy), policy)
    def test_s3_put_object_notification(self):