Try using hyperkv

It looks like [hyperkv](https://github.com/substack/hyperkv) does a lot of the stuff we want to do in our MVP. We can simplify a lot of our work if hyperkv fits our needs.

Try this:
1. Import 3 rows (JSON objects) into hyperkv
2. Add 3 more rows
3. Delete a row

If that works, we can try wrapping hyperkv with our importStream.

[hyperkv](https://github.com/substack/hyperkv) uses [hyperlog](https://github.com/mafintosh/hyperlog) instead of hypercore. If we want to use hyperkv, we should talk to mafintosh about the pros and cons.