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`
bucket_name = 'test-bucket-%s' % short_uid()
        self.s3_client.create_bucket(Bucket=bucket_name)
        data = '000000000000000000000000000000'
        
        upload_file_object = BytesIO()
        with gzip.GzipFile(fileobj=upload_file_object, mode='w') as filestream:
            filestream.write(data.encode('utf-8'))
        
        self.s3_client.put_object(Bucket=bucket_name, Key='test.gz',
            ContentEncoding='gzip', Body=upload_file_object.getvalue())
        
        downloaded_object = self.s3_client.get_object(Bucket=bucket_name, Key='test.gz')
        download_file_object = BytesIO(downloaded_object['Body'].read())
        with gzip.GzipFile(fileobj=download_file_object, mode='rb') as filestream:
            downloaded_data = filestream.read().decode('utf-8')
        self.assertEqual(downloaded_data, data, '{} != {}'.format(downloaded_data, data))
    def test_set_external_hostname(self):