Merge-ignore branch 'stalled/dagjson-bytes'.

I don't think we've resolved the questions already noted in that diff yet,
and I abhor drifting open branches, so I'm going to "merge" this
such that it's in git history for reference, but not an effected diff.

Additionally, I believe we encountered a question about whether this string
should include multibase -- this diff doesn't; the spec suggested it should;
and I think we've agreed the spec should be changed, but I'm not sure if
that's been done yet.

At any rate, someone's welcome to take a look at this again in the future.