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)
        
        for hash in ['__invalid__', '000']:
            raised = False
            try:
                self.s3_client.put_object(Bucket=bucket_name, Key='test-key',
                    Body='something', ContentMD5=hash)
            except Exception:
                raised = True
            if not raised:
                raise Exception('Invalid MD5 hash "%s" should have raised an error' % hash)
        
        self.s3_client.delete_bucket(Bucket=bucket_name)
    def test_s3_upload_download_gzip(self):