Replace DenseRowTextStorage with raw mr job

@markhibberd I haven't done anything significant here (yet), expect for order the dictionary the way it was. I'm assuming there is more we want to do as well but you didn't get time. I'm happy to finish it up, and might look more closely at what you've done after lunch.

/cc @raronson 
> I understand the cli tests to some extent, but the spec shouldn't be relying on anything but joining on the dictionary to verify the order IMO. I am not against sorting it, I just don't want it to be like it was.

I can fix the spec to use the same ordering (currently/previously it was just a hard-coded comparison and thus needed to be deterministic), but yeah we'll need to pick some arbitrary order (whatever it is).