level-orm not putting rows in a sublevel?

Hey @eugeneware,

I recently ran into an issue trying to extend this module and use it in combination with level-query. @maxogden pointed out that it didn't appear as though this module (level-orm) was storing the data in any sublevel.

Generating some test data with `npm test` (commenting out rimraf) and checking the raw leveldb seems to show values like this:

```
$ superlevel data/testdb createReadStream
{"key":"70c3bf7573657273c3bf68616e646c6539","value":"{\"handle\":\"handle9\",\"name\":\"name 9\"}"}
```

but we might expect to see something like

```
ÿusersÿ70c3bf6d657461646174c3bf31343134383533393330323032
```

I'm looking into it more now, but is there anything that comes to the top of your head why it might be doing this? (or are we wrong?)

I hope this might fix the problem as to the interoperability between level-orm and level-query, although i'm still relatively new to the internals of leveldb so some guidance is appreciated!